As a long term advocate for S-Gear, I have a hard time saying this, but Bias Amp is truly amazing sounding.  I wouldn't say that every model is better than S-gear or Guitar Rig 5 (which I also use occasionally), but there are a few that they have absolutely nailed.  In general, the Marshall sims they have are stunning, especially the '63 J45.  There is a welcome clarity there as well as a sense of pushing air "power" that is just fun to play with.  I also really liked the Hi Gain Diezel VH-4. 
 
This is without even messing with all the tube options, power amp switches and tone stack lists.  Anyone else have a chance to mess with this amp sim?  Its so fun!

Yeah, the first time I tried Bias Desktop I heard things I hadn't heard from any other amp sim.  More clarity, immediacy, and detail.  And it's a tweaker's dream, if you're so inclined.  
 
As of now, the basic package is still on sale for $69 -- a no-brainer, I'd say.
 
Cheers,
Eddie
 

Immediacy is the perfect word for it.  I know all amp sims claim "amp like response" or whatever, but that is exactly what I feel screwing with this sim.

I've tried the demo a few times and just couldn't bond with it. However I felt the same towards Revalver 4 until now. I'm sure it's just a matter of stumbling across a combination that I would like. One thing for sure...Amp sims are getting crazy good. I don't miss my amp at all.

BIAS Amp Pro is indeed awesome, as is BIAS FX Pro, for me they are both way ahead of S-Gear 2 and anything else bar TH2, TH3, If you want some truly nice presets, Patches for BIAS Amp, apart from what you can get for free via Tone Cloud, check out these
 
http://shop.choptones.net...d-bias-desktop-patches
 
Very nice. Although the installation is a bit of a pain, and the instructions contained in some of the packs have not been updated to match the installation procedure required for the latest BIAS Amp version ( they will email it to you, but you have to ask, maybe now they have that sorted though), once done, it is well worth it.
 
What I did, is install via the updated instructions, then save as is as my own preset, then for each subsequent preset/patch pack just replaced the folder names with the new, saved the file, then saved the presets out as my own, rinse and repeat, then just replaced the file with the original that I kept, and everything is fine (You don't have to take these steps of mine, but I did it just to keep the BIAS Amp file as original). Like I said, a bit of a pain, but well worth it IMO, they sound pretty sweet.
 
On a related note, they also have a pack for Amplitube 3, which is very nice, and for me was better than anything in Amplitube 3 or any of it's expansions, it also works with Amplitube 4, but whether or not you need both installed, which I had, I don't know, I no longer have any Amplitube stuff.

sven450
As a long term advocate for S-Gear, I have a hard time saying this, but Bias Amp is truly amazing sounding.  I wouldn't say that every model is better than S-gear or Guitar Rig 5 (which I also use occasionally), but there are a few that they have absolutely nailed.  In general, the Marshall sims they have are stunning, especially the '63 J45.  There is a welcome clarity there as well as a sense of pushing air "power" that is just fun to play with.  I also really liked the Hi Gain Diezel VH-4. 
 
This is without even messing with all the tube options, power amp switches and tone stack lists.  Anyone else have a chance to mess with this amp sim?  Its so fun!

I just tried the demo of Bias Amp and I agree with you about S-Gear. S-Gear is good and is my go to sim when I break down and use one. But Bias Amp is more inspiring to me.

It's all very inspiring to me!!  Makes me wonder where amp sims, and modeling in general, will be in 10 more years.