I can deny it and I do. My main spec is demo. My ilvl is 650 and I struggle to push out 20k DPS. I'm a fairly skilled player, so it's not like I have a poor rotation. Look at the level 100 talents. Demonbolt is a joke, you can cast it 4 times and you're done. Your entire Fury bar is empty. Cataclysm is a joke with that cooldown and cast time. Then there's demonic servitude. Yay new pets! Problem is, if you take that talent, you lose a burst cooldown and thematically it's the talent that should go with demo but it doesn't. Then there's the issue of a gigantic pet you can't see around or shrink in any way and all this wouldn't be so bad if their DPS didn't suck so badly. They're not much of an improvement over the felguard and certainly not worth losing them as the summonable burst DPS I mentioned above.
I have NEVER seen a warlock top the DPS charts since WoD came out. Considering that our only specs are for damage, that's a problem. That'd be like priests with their double healing specs coming in 6th place behind Death Knights. Right now in the sims we stand at 15th place. I'm sorry, but I feel like I should be able to out DPS the warrior tank in raids because that's all I am able to freaking do.
No weaknesses? We're still casters for one, so we die pretty easily. We are CONSTANTLY going OOM now in fights. This is something that was never a problem before and to my knowledge isn't a problem for ANY other class in the game. For a standard LFR raid boss like Imperator, I have to life tap at least 9 times and that's taking away from the poor healer's mana. (I love you healers, I'm sorry.) Our emergency self healing is healthstones, it's a joke. Drain life has been nerfed into the basement of hell and we have basically no ability to replenish life, whereas before, I could usually drain tank something and while not optimal, I'd survive. Even the warriors have things to heal themselves to some extent. Warlocks? Nope, we get a channeled, easily interrupted spell that sucks to begin with.
I could go on all day here, point is, yes, there is a major problem with the warlock class right now and any quick visit to the official warlock forum on blizzard's website will reflect as much.