I've used all 6 versions of Photoshop Elements, recommending previous versions to friends, and version 6 is by far the buggiest. The Organizer (the part that organizes all your photos) is riddled with bugs, some minor, some major, indicating a major lapse on Adobe's part. While 6 performs a little better than 5 for me (with 12K photos), and some people with larger catalogs says it performs much better, the bugs and new features barely justified the upgrade cost for me.
I'd recommend reviewing the problems people are having at Adobe's user forums ([...]) and testing the free trial available from Adobe before committing your money, especially if you're upgrading from a previous version. Beware that Adobe almost never releases patch releases of Elements - they release one version each fall.
Here are the bugs that I've personally encountered:
* Even when Help installs correctly, it is missing more than half its content, and the manual isn't in the online download or on the CD. (How is one supposed to know that much of the Help content is missing?)
* The menu bars don't display if you have changed the screen DPI to be larger than 96 (as many people do on today's ubiquitous high-res displays).
* The grey-on-black user interface can be completely unreadable or hard to read on many uncalibrated displays (e.g. the typical consumer display) and can be hard to read by older people with aging eyes (distinguishing dark is a known problem of aging, and middle-aged people like myself appear to be a primary target demographic for PSE).
* The File > Move command will silently and permanently lose a file if the destination folder has a file of the same name as the file being moved; this is different behavior than PSE 5.
* The File > Move command loses the association between the photo and the audio caption, even though it moves both files to the new location.
* On a multiprocessor, the Organizer behaves erratically with catalogs containing raw files: sometimes it crashes, sometimes it shows the hourglass icon for raw files, sometimes it shows the broken-image icon.
* In a catalog with large numbers of raw files, scrolling quickly over dozens or hundreds of large-sized thumbnails will consume 100% CPU for a minute or longer.
* Tag hierarchies with more than 500 or so tags make the Keywords pane unusably slow (but worked fine in PSE 5).
* Moving map locations always fails, silently (too bad if you want to record backcountry locations not namable via Yahoo Maps).
* Giving a map location to a tag assigned to hundreds of photos makes both the Keywords pane and the Map View unusably slow.
* Removing the map push-pin of a tag assigned to hundreds of photos mistakenly tries to update the metadata of each photo, which can take tens of minutes and fill up your recycle bin.
* If a photo with GPS coordinates is imported, it doesn't show as a red push-pin on the map.
* New dates set by Edit > Adjust Date and Time sometimes get silently lost.
* The Photo Downloader process APDProxy.exe crashes at startup because of a missing DLL.
* File > Write Keyword Tags and Properties fails to update the metadata of TIFFs produced by Nikon Coolscan V, Nikon Coolscan 5000, and Epson 4490 scanners.
* File > Write Keyword Tags doesn't write the map location (GPS coordinates) into the .xmp sidecar files of Nikon D80 or Canon G9 raw photos.
* The File > Write Keyword Tags command doesn't report any errors in writing the metadata back to the photo (e.g. unsupported file types, readonly files, corrupt EXIF data).
* The Organizer fails very ungracefully when two drives have the same volume serial number, e.g. because of the use of a disk-cloning utility.
* The duration of a video clip included in a Slide Show is set to the default duration, not the length of the video clip, and right-click Edit Duration doesn't change the clip's duration.
* An audio caption attached to a photo isn't imported into a slide show even though the option Include Audio Captions as Narration is selected.
Searching and Dates/Times:
* The timeline doesn't correctly display date ranges spanning many years.
* You can no longer exclude a parent category from a search, e.g. exclude all photos tagged with any tag in the People category.
* Find > By History > Imported On sorts the photo dates alphabetically, rather than by date/time, making the command almost useless, and it shows a scary message "Deleting Keyword Tags" for catalogs converted from version 5.
* Setting a date range and then excluding two tags from the search clears the date range.
* Show All doesn't clear a date range set by Find > Set Date Range (can be very confusing).
* Searching for "0 stars only" doesn't work for photos in a catalog converted from PSE 5.
* Save Search Criteria As Smart Album isn't available if a date range has been set but no other search criteria have been.
* Time "unknown" has two bugs: Editing a photo won't preserve time "unknown", and searching with date ranges doesn't properly handle "unknown".
* File > Write Keyword Tag And Properties sometimes fails silently to write the EXIF XMP Date Time Original tag to older .jpgs, even though several other tools are fully capable of doing so.
* Edit > Adjust Date and Time sets the wrong date/time for the EXIF:CreateDate field of JPEGs produced by an Olympus C50-Z.
* If a hard drive containing photos in the catalog gets its drive letter reassigned by Windows, then the left-hand folder pane of Display > Folder Location view shows the old drive letter, not the new one, as containing the photos.
* The File > Rename command no longer includes leading zeroes, causing the renamed files to sort incorrectly in Windows Explorer.
* In File > Export, the Common Basename can no longer be empty, and a hyphen is added automatically, so you can no longer get files named 1.jpg, 2.jpg, etc.
* Setting the Apply Metadata > Author or Copyright fields or the option Preserve Current Filename In XMP of the advanced options of the Photo Downloader causes duplicate files to be downloaded and imported.
* Display > Import Batch shows the wrong time for batches imported by the Photo Downloader; if the local time zone is UTC-8:00, then the time will be 8 hours earlier. Also, dates are shown as 2\20\2008 rather than 2/20/2008.
* With the Import EXIF Caption option turned off, captions pre-existing in a file's EXIF:ImageDescription metadata field reappear in the Organizer after invoking the Full Editor.
* In the full Editor's Red Eye Removal Tool, the Darken Amount is reversed: 1% produces the most darkening, 100% the least.
* Nudging with the arrow keys in the Editor stops working after applying a layer style, until you type Ctrl-T (Free Transform).
* The width of the Editor's Palette Bin can't be adjusted by dragging the left edge, as you can with all the other similar panes (Project Bin, Organizer Bin, Map View).
* Dialogs in the Editor sometimes bounce back when you try to move them.
* On a 1280x1024 display, the Editor Print window is positioned to perfectly obscure the scroll bar of the drop-down list of printer profiles, leading people to think their printer's profiles aren't available.
* If there are more lines than can be displayed in the Note field of a keyword tag, it is impossible to show the last line, though you can select it with Ctrl-A (select all).
* Copying a paragraph from Microsoft Word and pasting it into the Notes field of a keyword tag causes some of the spaces between words to be deleted.
* The scroll bars in the Organizer Full Screen view don't work correctly - clicking on the scroll bar arrows or the space between the arrows and the center box of the bar does nothing, unlike a standard Windows scroll bar.
* Escape doesn't close the full-screen-mode Properties dialog.
* Control-A to select all text doesn't work in the text fields of the Properties dialog.
* You can't use the Windows Explorer Tile command to tile the PSE Organizer and Editor windows.
* The Editor window can't be resized the standard Windows way by grabbing any edge, just the lower-right corner.
* Alt doesn't underline the shortcut letters of top-level menu items in the Full Editor (but it does in the Organizer).
* In the full Editor, if at least one open photo is minimized to the Project Bin, Ctrl-Tab no longer cycles through the open windows.
* In Create > Slide Show > Slide Show Preferences dialog, you can't use backspace or delete to clear the text in the Static and Transition Duration fields -- you need to select the text and then type over the selection (non-standard Windows behavior).