C'thun is possible now, did him yesterday on my warlock. However, you still take quite a bit of dmg in the stomach, so I would get the hell out asap still :P
Did Viscidus without any problems, didn't have elemental force or anything. Just nuked him. And he eventually froze, easy peasy.
Razorgore is laughable now, gotta love self-healing taking the aggro (grimoire of sacrifice). Before patch I had to use dark apotheosis as well, now I think I had to control the orb 2 times at most, didn't need to kill any mobs, seemed to be less of them. But that's probably because I did it much faster since they removed the cooldown to destroy eggs.
Reliquary of souls was probably the most frustrating encounter before this patch though, I could solo it. But I just didn't bother, so I always brought a friend instead.
Hopefully they will make more bosses soloable later on, as there's still a couple you have no chance soloing because of special mechanics.I wish they would make Kalecgos soloable too
In 25man I wouldn't mind a nerf to he's dmg, 10 man I can do without problems but 25man is still tough. Patchwerk 25 is worse though.I just want them to nerf the shit out of Razuvious at Naxxramas