Now you know how I felt when they nerfed lock dots. :P I bitched about it a lot then, but fast forward to now: I'm outcritting and outnuking mages and pretty much out-damaging everybody except for the occasional rogue. I synergize so well with a shadow priest it's not even funny. My solo efficiency is still fine. I don't know about the PvP situation for my class, but what the hell, I don't PvP. In Karazhan, it's practically required to bring along a lock for the Shade of Aran encounter (preferably two), Wizard of Oz, and the Curator. I'm not worried about not being wanted in raids anymore.

So while the nerfs seem pretty severe, I doubt in practice it'll be that bad in the long run. There'll probably be adjustments before it goes live, even.