The "exFAT" format, as shipped on this uSD card, was not recognized by by my Samsung Galaxy Tab 7 "Plus", and the tablet could not even reformat it.
Addendum: Here's what I've learned ... I ordered the "Kingston" 64GB uSD card, because the "SanDisk" engineers acknowledge that their 64GB card can only be formatted as "exFAT". There is currently a problem with any of the Galaxy family devices running Android 4.0 or higher, they can not use or format a card with "exFAT". There is a firmware upgrade available from Samsung that will fix that, but they are not pushing it to your device because they say it's not ready for prime time yet, so you have to go to the website and pull it yourself, and use it at your own risk. The alternative is to do what I did, which was use my Linux machine to reformat the Kingston card as "Win95 FAT 32 (LBA)". The (LBA) part is important, as that will let you address the full 64GB minus a little overhead for address translation. The only drawback I see is that it's a little bit slower, and you can't store any individual files that are over 4GB in size (personally that's not a problem, as I don't need any single files anywhere near that size on my tablet).
Addendum 2: The Samsung Galaxy forums, and Android forums, are saying that the Galaxy S3 (only the S3) running "Jelly Bean" (Android 4.2) will read and format "exFAT" cards. A further caveat is that if you use the card encryption setting, or want to use the card in recovery mode, it can only use "exFAT". What this means to other Galaxy devices, if and when they get upgraded to "Jelly Bean", remains a mystery.
Addendum 3: Someone bitched at me for not having my facts correct, so I decided to add this addendum. Here are the facts: My original facts were correct, in fact straight from the horses' mouth. The engineers at SanDisk at first simply said "You Can Not Reformat The Chip", then later admitted that there was a manufacturing flaw. If you have a chip manufactured after Jan. 2013, you can reformat it, if you have one manufactured before that, they will replace it for free. Please note the date on my original review was Feb. 2013, we didn't know about the updated chips at that time, and I apologize. All I can say is, if you're sure you're getting one of the newer chips, go ahead and try it ... also, go to the SanDisk website and read it for yourself, there's some caveat about the date on the packaging, an old chip could come in a package with a newer date, or some such thing.
Bottom line (as far as this review goes) is ... the "Kingston" 64GB uSD card will let you swing both ways, while the engineers at SanDisk say that (some of) theirs will not.