Splinter Cell: Double Agent: Worse than Chaos Theory in every way... and this one frequently crashed and had inferior graphics. Thankfully I only paid $10.
Battle Stations Midway: I bought the game and it would not install. So I downloaded it, and even the download did not work. I made sure my system was clean of any crap from both versions, went back to Frys and returned the game. Thankfully they gave me my money back even though I opened it.
Metro 2033: In the year 2033 I'll have a PC that will actually be able to run it. In the mean time I'll just enjoy Crysis at near maxed out settings.
Battlefield 2: Awful for online play with the "punkbuster" crap. More like playerbuster. It kicks you out of the game for no reason. I never played it for more than 5 minutes online. Thankfully I only spent $10. I should have tried to return it, but never did.
Team Fortress 2: Extremely boring and lame. I paid $40 for the orange box. IMO, Ep 2 and Portal were only worth $30 together, so I felt like I paid $10 for this. I would not even pay $2 for it.
Those are some I can think of off the top of my head. There are more though.
It seemed to try to straddle the line between UT and a futuristic war shooter and didn't really capture the fans of either. The menu systems were consoleish. It didn't have AA. But biggest of all for me was no one played it and most of the modding community, which was pretty much the entire reason I bought UT2k3/4, had moved on to Source.
The main thing that killed it for me was the lack of big maps and little to no custom maps.
The vehicles felt underpowered to me.
A lot of the maps did not have any Raptors, or only had 1-2.
Overall the game was not as vehicle oriented.
There was not as much content either.
Some of the maps were so small and pathetic... like the one where your Goliath can only move forward on a near straight line, sits on a platform, and shoots at the exposed power core.
But I did laugh at the opening cutscenes.
Overall I had my fun with the game, but it was not as good as 2004.