I am too much of a purist to really enjoy tributes, but I fully accept that loads of people are not as picky as me, and an approcimation of a band they like will do just fine.
On my recent cruise holiday, The Beatles Experience were on board, doing two sets, early and later Beatles and they were really good - the later Beatles material was not written with a view to live performance, they were a studio band by then so to do these songs well was not easy. I would go and see this band again, but had they played locally before seeing them on the ship, it's unlikely I would have gone along.