Considering that the game has been back in the NPD top 20 sellers for the month of march (the only MMO there besides wow, a piece of news news that massively must have missed), I'd say yes, many people are still playing the game.

http://kotaku.com/5215458/and-the-20-top+selling-pc-games-for-march-were

The fact that it's back on the sales charts is quite a positive signal, that shows that the recruit a friend program and the free trials are working well, and that the game is getting more and more polished and fun.

When the land of the dead hits you can expect a sizeable percentage of users resubscribing as well, in spite of the doomsayers and the trolls.