I'm a former DOD junky. DOD:S is a perfectly acceptable FPS shooter. It's a bit thin on maps (maybe 10 total official ones) and only 2 modes of play (CS-style (protect the bomb) and classic DOD). There are probably 10 more custom (user created) maps that are of high calibur. There are also other mods (Warcraft, zombie mods, deathmatch mods) that can be a lot of fun if you get bored of the main game.
During peak hours (8pm-2pm EST) there are probably 1000-2000 players playing at any given time. Not bad .. but no where near the amount of players that play CS.
Just remember that keeping a 1:1 Kill/Death ratio in this game is VERY good. So, don't get discouraged if you end up with 10 kills and 35 deaths for the first couple of times playing. The game rewards SMG users due to the speed of the game (players move FAST).
The respawn timer is set for every 12 seconds.
I think its definitely worth 10 dollars. Just do some reading on how to optimize your game (the kill messages are WAY too big for instance) and some of the effects are meaningless and drag on your FPS.
