I'm going to break this up into a few parts:

Shop:

The shop is... weird. I like the idea. I always liked the shop in DotA 2. I like the recommended tab (though I wish the items were a bit less off base). I like the search bar. I like the new filter feature - however, I do NOT like the way the items are listed. If you have the names showing, it's only one per. If you don't, it's hard to distinguish.

Also, it's way too ****ing big. If I move it to the top of my screen, it STILL covers my skills.

Scorescreen:

The font is smaller. It's harder to read. It's bigger than it needs to be. It looks nice, it's just too big and too gaudy.

Rest:

I like the new champion icons on the left.

The top right area looks good, in my opinion.

The minimap is good.

I find the bottom left interesting. The amount of gold I have isn't instinctive to see for me anymore. So is the experience bar. The rest, however, is fine.

The skills and HP bars are weird as ****. It's weird to see how much HP and mana I have now. Also, it's a bit too big.

The surrender screen looks ****ing retarded. You should probably reprimand whatever moron did that.

Overall:

I like the idea of redoing it. However, it feels wrong when I play now. I've noticed my gameplay has gotten less polished after the update. I wish there was an option to switch back to the old UI. I could deal with the mediocre shop interface if I could use the interface I found fluid and natural.