I love mine! I have a full suspension Salsa Bucksaw and love the hell out of it. I do agree with Dave that they are not the fastest bike around but I can say that I keep up with almost everyone I ride with as long as it's not a super technical downhill.
I ride a dirt bike all summer and when it came to cross training on my skinny tire bike I didn't always feel comfortable with how it washed out in decomposed granite and other loose terrain. The fatty rolls right over such terrain in places like Buffalo Creek area!
It puts a smile on my face and all my other buddies that take it for a spin. Now 3 years later (after my purchase) I would maybe do another bike such a the Yeti SB5+ but that's new technology and trends for ya. I honestly don't think I would but a skinny tired bike unless it was used strictly for road use.
Suggestion for anyone on-the-fence, go rent and ride a plus sized tire bike on a trail and you will see how well it climbs as well as how it handles on the downhill!
To each their own..I'm not out to break speed records. I'm out to have a great time and keep up and my one quiver bike does that just fine!
Happy riding folks!