I was about to buy one of these when I was amp shopping. I had done all my research and everything. When it finally came down to the time to buy one I bought a Vavleking 212 instead. I had read a lot of bad reviews about the Vyper line. There are a lot of lemons out there. I remember I asked the guy at Guitar Center if he had heard the same thing. Of course he said no. He went to show me the floor model.....and of course it was dead. So he said he would bring out a brand new one. He brought the box to the floor and we opened it right there. Plugged it in.......and also dead. Sure that was probably a REALLY unlucky batch, but it brought up some red flags.
The final thing that made me change my mind was the tone in the end. With modeling amps like, I personally feel you are paying for a ton of bells and whistles, but if you compare it to another amp in the same price range, the tone suffers a bit. They do sound good in videos and stuff, but once you compare in person I feel that it sounds kind of "fake".
That was just my experience and opinion though. In the end it's up to you what sound you want. Just ask yourself if you actually really NEED all the features of the Vyper. Also consider the extra cost of the foot pedal. You can only get the "Sanpera" or "Sanpera 2" (pretty sure thats what they are called if I remember. The 2nd one unlocks the full potential of the amp, but you are adding on another $200 to your price.
Edit: I went back and found the thread I made when I was looking for an amp a year ago:http://www.guitartricks.com/forum/showthread.php?t=29180&page=1&pp=7
And another thread I made after I bought it. Worth a read to save you some money. The site is no longer selling this amp but the idea is the same. Shop around before you buy:http://www.guitartricks.com/forum/showthread.php?t=29395&page=1&pp=7