Many problems, but still pretty decent stuff.
First, THERE IS NO MULTIPLAYER! While this sucks a lot, considering that the multiplayer in Tides of War is pretty good, the single player game is good enough to compensate the lack of split-screen or online modes.
Another problem is the lame A.I. While it's better than in XIII, the artificial intelligence in RTCW suffers from a few glitches. For instance, enemies won't even search for you if you make a noise, except if it is a scripted event.
Another gripe RTCW has is the sound. Really annoying voice actors (how come the Germans speak English all the time?) and bad sound effects (normally I don't care about sound effects, but they're really bad in this game) really spoil the fun of the game. At least the weapons sound realistic.
Return to Castle Wolfenstein is a good FPS, but...