I've bought all the UFC's "best of" DVDs (2007, 2008 and 2009) and this is definitely the best of the 3. For starters, it contains 20 fulls fights, compared to 17 on best of 2007 and a measly 11 on best of 2008. They've also got the selection pretty spot on in my opinion in terms of best fights of 2009 (although opinions will always differ on this). The DVD does not include Machida - Rua though, which was an excellent fight, but if you buy Best of 2009 and UFC 104 you're pretty well covered in terms of best of 2009 IMO.
What I also like about this DVD is that it gives a good review of the year division by division, covering some fights (Machida - Rua for instance) that weren't included on the DVD. Also has a nice section on Chuck Liddell, who was inducted in the UFC hall of fame in 2009.
Overview of fights:
Lightweight:
Sanchez vs Guida
Griffin vs Franco - loved this fight, dynamic performance
Diaz vs Guillard - excellent BJJ display
Sherk vs Edgar - great, high paced striking match
Stevenson vs Diaz - great grappling match
Penn vs Florian
Welterweight:
Hughes vs Serra - good, close fight
Condit vs Ellenberger
GSP vs Penn - great performace
Swick vs Hardy
Middleweight:
Marquardt vs Maia - violent finish
Franklin vs Belfort - good technical striking match
Quarry vs Credeur - close back & forth fight
Light heavyweight:
A Silva vs Griffin - dominant striking display
Evans vs Machida - also, dominant striking display
Liddell vs Rua - same again
Jardine vs T Silva
Bonnar vs Jones - one of my favourite fights on this DVD, very dynamic striking and wrestling
Heavyweight:
Lesnar vs Mir - scary performance
Nogueira vs Couture - very good fight from both fighters