:^) I think they're still bloody good most nights.
I once saw them very lacklustre in 2003 (lotsa Purple fans were underwhelmed by that tour). And Ian Gillan's voice was a bit unreliable for a few years, but seems to have got better.
I think if you like 'em (I do!) & have realistic expecatations (ie that it's not 1971-2) they're great. Never gonna be like in the 70s, but they do it for me!