My personal thoughts about the program:
1. I'm not sure how it works on Windows 7-8, but on XP it gets pretty laggy :<
2. There are many brushes - REALLY AWESOME BRUSHES with cool options and stuff xD
3. Even though there is something like Sai's stabilizer - it's not as good as in Sai. It's pretty good anyway.
4. There are plenty of options for brush settings and layers and such - pretty much like in Photoshop.
5. Perspective grids. OH GOD. Took me some time to actually get how it works, but it's awesome and WOW and... xD
6. I'm not a big fan of it's color wheel. Not sure how to change it, but it's probably pretty simple.
7. I'm not sure if it's just my computer but i had to click some things twice to make them work (and i don't really like clicking twice on one icon xD)
8. It's a good program, with lots of cool features. Good if you don't want to switch between Photoshop and Sai while working. It's good if you've been drawing only in photoshop since stabilizer is a great thing while drawing and Photoshop lacks it.
9. I'm not sure about it's photo editing abilities, but it's safe to say that photoshop is probably the best for this kind of art - mostly because of how many things you can do in it and how many new brushes/actions/sh*t like that you can put in it.
10. KRITAS MASCOT IS THE CUTEST LITTLE THING EVER!
11. Not a fan of it's vector drawing style. But let's not forget that it's not a vector program xD
So... Krita is pretty awesome, if i had a better computer i'd probably work with it. I still prefer Sai for drawing lineart and coloring, but if you're looking for a cool program that works like Sai/Photoshop and is free - KRITA is right for you.