Quake4 sucks and I am holding this man hostage until I get my 50 bucks back:

Where to begin...
Yes this game is better than Doom3, but really, what isn't?
The level design was awful. Every interior section is cramped as hell and follows the typical box room, door, box room, door, hallway, door design from D3. This is probably a consequence of using the D3 engine, which begs the question: Why use it if thats all you can do with it? There's no variation in the basic map designs and I'll be damned if I can recall a time when there was significant vertical axis combat outside of the outdoor areas. And holy s**t, the outdoor areas... it's comical that an engine as 'powerful' as the D3 engine can't manage to create an outdoor section with a fraction of the detail of the interior sections. Seriously, the outdoor areas could have been ripped from Half-Life they are so blocky and undetailed, and I'm sorry but 2d skyboxes don't cut it anymore.
The AI is dumb as dirt and presents no challenge at all. The only enemies that had an inkling of 'intelligence' were the orange suit guys, and that consisted of hiding behind a box and taking potshots every once in a while. The problem is they don't run from that spot if I shoot a grenade there, and every once in a while they will face the wrong direction and just stand there. Often if they charge at you or you charge at them they won't fire and just die. They don't flank, they don't use grenades, they don't cover for each other. I'd guess that these guys are given 'hints' ala HL2 as to where to stand and cover, but it's nowhere near as flexible or correctly implimented.
The friendly squad guys were cool enough, and I liked my squad enough to feel bad if they bit the dust. However, teammates like these were better done in OpFor where they actually were useful and awesome to fight alongside. Sure, the Q4 guys could kick some ass, but its not very hard to do when they can kill big badguys in like 2 shots and are invincible. Yes, they are invincible. Any time in the second half of the game when you are with a teammate you can just let them do all the fighting with no consequence to yourself, which kinda removes any challenge or any feelings of 'I gotta keep my guys alive and if they die its cause I dropped the ball.'
There were some awesome parts such as the pod ride and other things I won't spoil, but for every awesome part there was an embarassingly bad part like the hovertank sections and the rail shooter sections. And seriously, the hovertank section was probably the worst thing I have played in ages.
The game isn't hard either, I died more from getting caught on details while backpedalling or from my own splash damage from rockets and grenades than I did from monsters.
The multiplayer is pretty much identical to Q3's which is not my cup of tea but I'm sure others like it. I'm already bored by it though and I'm sick and tired of sticky lag and other funky things that I haven't experienced since I was using a 26kbs AOL connection while playing HLDM back in 1999.
I've beaten the game already and frankly I doubt I'll ever play it again, so it will be gathering dust next to Doom3 as another game that I'll never touch.