I chose UC2 as my first PS3 game in 2012 and wasn't disappointed, but the combat can get very annoying due to slow camera and bulletsponginess of the enemies and often only one right path during combat which often means if you move, you die. The puzzles are designed for 5 year olds. Despite the shortcomings UC2 is undoubtedly the best UC game and one of the best action adventure games of all time.
UC3 was a disappointment for me, technically it is one of the most impressive games on the PS3, but the combat is even more annoying, the pacing is hectic and some of the puzzles make no sense.
UC1 I haven't played because it is considered the worst of the series, with waves and waves of enemies - not my kinda game.
UC4 I don't know how to feel about - when you actually get to play it, it's quite good, I mean I like stealth action over regular action, but the problem is that you have to spend so much time walking and climbing, it is especially bad on replays.
Golden Abyss - UC on a portable makes no sense to me, I played the demo and was glad it was so short.
Lost Odyssey - if it is ever 5 bucks I will grab it but I'm keeping my expectations low.