The only reason I didn't give this 5 stars is because of something I noticed during "The Great Salmon Run" episode; ugly vertical lines. It seems that some of the video clips might have been used from separate/other sources, specifically the slow motion shots of the bald eagles catching salmon, and some slow motion shots of the bears. At first I thought there was something wrong with my new tv/playstation 3 setup...but after a little Google searching I found a couple other people noticing the same issue with the vertical lines on this particular blu-ray disc, and specifically during the salmon run episode. However, I think this is one of my favorite episodes in the series, so I can easily get over a couple shots with lines through them.
In short, just in case anyone else comes across this issue, it is not your tv or player...it is just the video on the blu-ray disc. I have never noticed this issue with anything else I play. Hopefully someone with the same problem will read this review.
On a more positive note, overall I love this series! It is very similar to Planet Earth, but most of the amazing events are based on the migration of many species and the changing of the seasons in different locations around the globe. There are some really amazing shots and really amazing events, definitely worth getting this blu-ray.
One of the best features of this series is the Diaries, which can sometimes be more intriguing than the amazing events themselves! The Diaries for the salmon run and the great feast are amazing. The camera crews are really quite privileged to do the things they do. I almost think BBC should release a series devoted to documenting their camera crews. It's just incredible, some of the things they go through.
Another bonus, as mentioned in other reviews, is the calibration walk-through included on the first disc. If you haven't done anything like this with your tv, do it before you watch this! It really makes a difference...and remember to disable any special "enhancement" settings your tv might have, like "enhanced contrast" or "super white" or anything along those lines. Any video released on blu-ray wasn't intended to be viewed with all these enhancements and is calibrated for performance without any special extra treatment.