I get the impression that the game only superficially adheres to 4e rules.
It bases various powers/feats/etc on 4E design and structure, in the same way that NWN did on 3.5 - and, in the same fashion, other elements are simplified to account for real time combat. Powers and spells recharge over time rather than requiring rest, no AoOs, etc.
I think anyone familiar with any edition of D&D would find it readily recognizable, and its probably worth trying out the demo to see what it is like.
For myself, given the relatively cheap price, it looks to be a fun but mindless game to go dungeon crawling with friends. It isn't especially polished - limited voice acting, some static image cut scenes - but the combat and dungeon crawling itself is fun. At least, thus far - I'm only about a half hour into the game.
The main limitation is not having especially robust options for character creation. You get a bit of power/feat/weapon customization within your chosen archetype, but it still is a bit of a shame. Still, again, for a Gauntlet style dungeon delve, as compared to a full-fledged CRPG like NWN, I can't complain too much.