A guitarist that can feel their guitars shake when an amp is often going to play better in my experience.
I have only ever used an amp-sim for the main tone about 2 times in total.  But.... when I do I'm super happy I have a tool that does it well.

I guess to answer the OP and the topic here...
I own a UAD card and they also have a new Amp Room plugin package.  I've heard great things, but until Guitar Rig can't do something I need it to do... I'm sticking with what works ;)  Same goes for TH2.  Till I need more, it's not worth it.  I use the tools I know fairly well as much as I can.

I've heard great things, but until Guitar Rig can't do something I need it to do... I'm sticking with what works ;) Same goes for TH2.

 
This is a common sentiment.  I guess if I hadn't gone GR 5 when it came out I would need a better sim.
 
I also agree with the other Brian - - - I prefer using my JCM 800 with the right stomps and the trusty SM 57, but having a decent amp sim throws in some great options!
 
Thanks All!
 
Brian

I've had a change of mind about the bundle offer. I may now go for it.
 
Not because I'm excited about the ampsim, but because of the full version of Breverb 2.
 
I decided as one last step before I ruled it out, that I would watch whatever demos there were on Breverb 2 on YouTube.
 
The guy that does the official demos has a pretty strong accent and he doesn't actually tutorial that much in his tutorials, but the clarity and flexibility of the reverbs he demos really suited my ears.
 
The demos really caught my attention. Very natural sounds, but great flexibility.
 
Now I'm heavily leaning on taking advantage of this month's sale before it goes away.

Yeah, taking advantage of the APRIL2013 15% off promo gets you a couple of bucks off the BREVERB 2 upgrade deal and a free TH2 upgrade. If I did not already own TH2 that would be a pretty compelling deal.