As a big fan of the 80's Hard Rock scene I would die to see two of my ultimate fav bands play together. I don't get the hate towards Crue though. The situation with Mick is complicated, they did offer him more money but he never answered back to their offer - John5 is doing an amazing job-, yes Vince isn't in the best shape that he could be vocally but he's a man in his 60's, his system is full of alcohol and drugs and the matter that he still manages to get his ass on a stage it's great (he's been through a lot you can see the pain is his eyes), don't forget you're the same people who criticize Axl about his voice.
Crue are playing LIVE they do have backing tracks for layering and backing vocals (Kiss, W.A.S.P., Def Leppard etc are doing the same) and yes Nikki is playing live. I saw them last summer with Def Leppard in Prague and it was totally live, you could hear mistakes from Nikki here and there, Tommy did lost some beats too. Overall people had great time as much as the band, that's all that matters.
In conclusion I'm totally in for a GN'R-Crue tour.