Sometimes in RS/UO when a team I wasn't controlling was holding or waiting for a go code they would just die somehow (maybe my planning sucked), that "OH CRAP!" effect didn't really exist in RvS. It was like that too in MP to an extent, RvS MP was so predictable. The only real challenges were self imposed, like everyone deciding to go pistols only or something.
Also weapon implementation was horrible, theres obviously a reason everyone always used the L85 or G36K. I've seen someone take 283 shots from a P90 to center mass before dying (it was like 76 or something before being wounded).
Another thing I hate which is not really RvS specific is being able to run while zoomed in. How realistic is that?
Some MP specific points (survival mostly): RvS was so devoid of tactics, it was always just who had a faster mouse or was luckier. There was zero stealth. Map and spawn point design were so bad, you either went one way or the other and might encounter the other team, if you didn't then you would go to the other direction and open fire cause they will be there.