It's good, but it really isn't as good as regular HL deathmatch. There are barely any servers where as HL: deathmatch has over 100 and it really doesn't have any graphical improvements. Basically just like HL:S I was unimpressed.
It's better than HLS, anyway we could build new maps with improved graphics for it, so it's not just a game, rather a platform on which mappers and modders can built own stuff (some like Alien Swarm or HL2DM).
Anyway, original HLDM I like much more.