Recommendation for this game? No.
This game is extremely fun in my opinion but it's dead. People have tried getting it popular but they have failed. If you're going to get hl2dm you mine as well not get in and get hl2 instead. hl2dm is dead period. It has less than a population of 200 and doesn't provide much content(since it's old) and isn't updated frequently because Valve doesn't give a ♥♥♥♥ about this game. I've seen a lot and Im thinking the game is going to die(as in 10 players tops everyday) somewhere next year or the year after that.
The game can be fun and all but the only I reason I would get this at this time is play RP servers and socialize. Other then that there is no point in playing this game.
No, only if you want to play a good game that is populated + this is a multiplayer "accident" game.
But for RP? If you like RP then try it out and try a decent populated RP server.