It's lite, it's simple and you can start using it very quickly. No need for thinking. The UX is fantastic and it's very intuitive. I was looking for a tool like this for months and it does everything I need (very simple, black and white to the bone wireframes)!! If you're a lite user, you'll love it.
Lite, easy to use and quick to get started
May be too limit for some (but then you should get sketch anyways)
I don't like it when products hold be hostage with assets i created on them. I find it pretty low.
Simple to use
Pricing model leaves you without access to work done. Not a fun experience and time lost. Thanks.
Ohh.. and work isn't saved as you go...