Everton were pathetic so I think I'd give Lukaku the benefit of the doubt for the end of season tail off. His scoring record for West Brom and Everton is very good so it's fair to suggest he could become a serious player in a better team.
My only reservation about him is that he can be a bit of an oaf, he's not a very polished striker. He reminds of a bit of Adebayor when he first joined us. WUMger managed to elevate his game though so I think he could do the same again.
I'd certainly be wary of the £50m+ price tag though, think we could probably spend that better but if we're talking about Premier League ready solutions, then Lukaku fits the bill.