Should you be afraid? Only if you are afraid of greatness!
The viper isn't the best in any one category, but it is amazing as an all around sled. Like all sleds, it has some known issues. If you are accustom to Yamaha fit and finish, it isn't quite there. I suffer from the off idle pop and mild kick back which makes me fear for my starter. I've changed my habits and hold the key a second or two after ignition to minimize the likelihood of kick back. I have faith that this will be fixed in the next re-flash and it appears that Yamaha is taking care of the problem sleds.
I saw all the same nay sayers out there that is probably influencing you which made me hesitate. Due to a bad back, I was looking for the best riding position first, an awesome suspension second, and a four stroke third. This was the first time every brand was on the table as my upgrade was a medical decision necessary if I was going to continue riding, and yes that includes Polaris

. With less than a half a season and 600 miles behind me, the only thing I can tell you is that I can't be happier with my choice. I'm more comfortable then ever on a sled. I can out turn nearly everyone and I haven't dialed in the suspension yet. I can keep up with or beat an Apex to 70+, and I have confidence a bit of clutching will allow me to hang with it a bit longer. My fuel economy is amazing at over 115miles on a tank and not babying it! I'm riding faster than I've ever rode before not because I'm a fast rider (I ride with an older group...), but because the sled is so comfortable, inspires confidence and I don't realize how fast I was riding until someone on another sled makes a comment! Everyone who has had seat time on my LTX-SE has fallen in love with it to include the bashers.... It's funny to me now when I hear the snide yamacat remarks. While this just reinforced that arctic cat quality isn't as good as Yamaha, I cant deny that they designed a great chassis. I know in the back of my head that I can keep up with the bashers in the hole shot and spank them in the corners if I want, all while being comfortable.
Keep in mind that this sled isn't a speed daemon and you won't be happy if you are expecting to beat an F1100 in a lake race. This is comparable to a 600cc sled with a lot more low end grunt then a 700+cc. If you are a speed daemon, check out some of the guys doing turbos. Sounds like they are having a ball! My thing is 0-80mph. I'm thinking real hard about a turbo...
Keep in mind when reading that the snowmobile industry is filled with extremely charged brand loyalty. The biggest crowd is Ski Doo. If you subscribed to group think, they would have the best quality, fastest and most comfortable sleds. While they have pioneered the latest suspension design, all the brands have managed to keep up with or exceed their sleds. As for quality, take a look at their 800HO engine. Its rare that it will go more than 7000 miles prior to eating itself. Their 4 strokes are nowhere near as good as Yamaha. Now Ski Doo was my runner up and I have had good experience with Ski Doo. My only point is every brand has their strengths and weaknesses. The Viper is no exception but all in all it is an incredible sled.