The map is much more busy, there is some kind of objective everywhere. Bounty runes are now required to take for a support, no ifs or buts. Ogre takes enemy bounties. Shrines are every bit as nuts as I thought they would be. XP goes a lot faster, I was lvl 23 40 minutes in, granted with 4/4/22 and 140 LHs + 25% xp talent on top, but hitting 25 45+minutes in will be viable.
The UI isn't as bad, but it needs customization, badly. It also abandons Dota's RTS roots, your hero staring at you all game long is useless, I don't want checking the enemy inventory to clutter up my screen. First thing I did is expanding the minimap to max size possible and the skins can still cover its edges, not being able to see who is in your fountain is annoying. Shop somehow allows you to do less - you need to keep switching between advanced/basic items all game long, since recommended now take up all space. Stacking is still viable, but only at specific timings or if you can stack more than 1 camp.