Love it. 2.4" in the back, 3.0" in the front. Doing a lot of extended rides on a mix of pavement/off-road conditions with lots of climbing.
I built this bike specifically for dirt touring, hence the simplified drivetrain (I'm young, SS isn't for everyone, gears are fine too) and the Jones bars. The geometry is dead-on for me because I am a tall dude at 6ft. I do not think my girlfriend would enjoy 29+ wheels because she's only 5'7". We are looking into 27.5+ for her.
There isn't a significant increase in rolling resistance with the Vee Trax Fatty. The tire profile is very round, so at 17-20 psi the center tread rolls very fast on pavement. I alternate my skinny-tired Soma Double Cross and this bike and don't feel slow and sluggish. The Maxxis Ardent in the back is also a quick one.
Certain tires, like the Surly Knard, are decent rolling. Others with huge knobs, like the Maxxis Chronicle, may be a lot more of a pain to push. I like where the Vee Trax Fatty sits, it is a very high-quality tire.