So its safe to say that a fat bike can be ridden all year long? Summer pavement/dirt. I have been looking into a fat bike. The fatboy in particular, this would be my second bike but was thinking it was 1 dimensional.
Of course, it's one of the huge advantages of fatbikes vs. snowboards or jetskis. You can't go snowboarding down the ski hill without snow or take your jetski on dirt trails, yet you can take a fat bike and ride it just like a normal mountain bike, abet slower and more sluggish. You can even switch the wheels out and build a 29er wheelset usually, but that's not necessary at all.
I rode my fatbike extensively last summer while saving up for a more all-mtn type bike. It jumped just fine, rode fine, etc. It's a LOT more characteristic of a rigid bike in the summer compared to riding on snow in the winter, you can't get away with the ultra-low PSI because it just pedals so terrible when you try to pedal out of the saddle and the tires squirm when you try to turn. If you know what it's like riding a 29er rigid bike, then you'll be prepared. It's also slow to accelerate and if you get going real fast you'll notice the huge gyroscopic force that will make you slow down quite a lot before any kind of sharp turn, but it's just like how you can drive a truck on a road vs. a sportscar, or maybe even better, like how you can ride a regular mountain bike on the road vs. a roadbike. Sure, the mountain bike won't be "optimal", but it works just fine, you can have some fun, etc.
On the other hand, consider the negatives first. The fatbike is in it's element in a place where you get enough snow that it covers the ground for months at a time, where trails get packed down from traffic, where people go out and do winter sports. If you're getting it for the novelty factor, it may be fun for a little while in the summer, but it may get old fast. A very strong rider may not see many issues and keep up with slower guys just fine, but it'll likely magnify the effects of a weaker rider on a hard-to-accelerate-bike.
But by all means, they handle the summer trails just fine. You see people out here riding them in the summer.