I don't suppose any of these old games are substantially better than DMC 4. I played through that and didn't like it much. Didn't like Bayonetta either, which seemed similar. I guess I'm not into the hack and slash games where you're graded on your combo chain, style and variety like that.
Pretty much answered your own question bud. No point in buying this then, DMC 4 storyline/gameplay wise felt lacking IMO compared to DMC 3 which is easily the best out of the series (you know, before Capcom went ahead and fucked it up by 're-imaging' it, again.)
However, Bayonetta is also easily one of the best hack-n-slash games, and now that Ninja Gaiden looks pretty dead, I'd probably say it's the only worthwhile title this gen that is inside the 'hack-n-slash' which really isn't all about that in higher levels.