i used to play it loads even when it was dead.
if u want to find games dont search on team deathmatch, that never works u need to find the people who are playing and get in a party to try that.
what u need to do is pick quick or medium length game on ranked for everyman for himself deathmatch. then just wait a few mins for people to join evntually you'll find the people playing
now i aint played for like 6 months but it was like this even a year ago.
one way how u can check how many people play the game is look at the leaderboards.
look under the monthly and weekly leader boards and just see how many players come up
if i rememeber rightly these 2 boards are mixes up, monthly is weekly and vice versa (u can tell of the stats how they dont add up and monthly is lower than weekly lol)
but u can see off there if people are playing. its just the lobby system and matchmaking is a bit crap so u cant see what games are getting played.
u just have to sit though first on ranked deathmatch (non teams) on medium length or quick length games and u soon find a few people playing then u can play teams or everyone for themselves. then as u find the hard core players add them to ur friends list then build up a list of a few and then u can just get invites to the partys. i used to enjoy it loads going to get it back coz u end up playing the same group of people if u play the same time every night. and can have good chat/fun/banter and also realistically u can do well to climb the monthly leaderboards. im no pure whizz but i managed to get to 28 for the month was quite pleased. looked to me they was still over 2000 players every month when i used to play
the frustrating part is just finding the party when u dont have no contacts for it but if u stick it out and wait a while for peoples game to finish and they party to return to the match making then u soon get hooked up with some players, and odds on u'll be host since u were waiting longest and it has a heavy advatnage too