Hah, seems a bit of a no-brainer to ask how many enjoy this game - I've not met many who didn't enjoy it. I personally love pyro and soldier, make a successful medic and am loving the heavy now there are unlocks to work for.
However, before unlocks were announced I'd stopped playing for a few months. It just got boring, endlessly replaying the same few maps indefinitely. I always prefer something to work towards, whether it's unlocks or levelling up or, you know, something. So long as there's a point (though I still dislike mmos, lol)
I know of a few people who liked it but felt no inclination to keep playing, but wither they were console gamers or it was before unlocks were introduced.