As I'm building Grabee it sometimes gets hard to just focus on the one main factor while building the MVP.
For me, this factor is the core feature of the product, and make sure that it's easy to use. Because I believe if you can't explain your product in a sentence, then it's too complicated.
Also, if it's too complicated, then people won't use it.
But what's the single most important factor you look for when building an MVP?
Pebble
Pebble
HyperSwitch
PHPRunner
Vikara