Yeah, random bosses are always cutting my winning streak into nothingness, especially Vergil. Because of them, I hardly have the patience (and skills, lol) to play the Bloody Palace. To clear all the 9999 (or 10 000?) floors seems impossible to me because of that. If they just put the player against regular enemies, not bosses, I think I could blast through the ordeal, but then again, it could prove to be boring to slice and dice for hours just so that you could say you've done it.
But I don't know how Bloody Palace is in DMC4; I must admit it that when the game came out, for some reason I held no interest towards it. I just played my other DMCs and thought that "well, maybe I get it later... if at all". But even if there are much complaints about the game, I guess I could buy it and give it a try while waiting the DmC one to come out.