I have the opposite opinion about the graphics. HoN can certainly get a little busy during a team fight, but DotA 2 has a couple of really big problems in its graphical presentation right now: In what I can only assume is meant to be a throwback to DotA because that makes it only very slightly less retarded, the physical scale of some heroes (Dark Seer pops immediately to mind) is too small and/or their visual style is too close to a creep that it is difficult to pick them out in a team fight.
Abilities and their effects can seem very disconnected, and sometimes hard to track in team fights. Lich's ult in DotA 2 is a little ball that bounces around. It looks completely non-threatening and the effect gets lost easily, despite it being one of the strongest spells in the game. Plague Rider ult's trail and sound effects immediately make the power of the spell apparent and the progress of it during a team fight is very easy to track (making it much easier to do the most important thing: Swear like a sailor at the dumb guy that leads it right towards you when you've already gotten away).
Another example is Lina v. Pyromancer. Even with
remastered graphics (I do like the scorched ground effect), the cast animation is pretty lame (why the hell is it shooting out from her spine?) and there is absolutely no indication other than healthbar that Sven is even touched by it (and the graphic doesn't match the cone). Now in
this clip, even though the video quality is awful, you can still see the difference. The spell is actually being cast by the hero, and the impacted heroes have a short-lived orange glow. Shadow Priest just has a bunch of purple swirls going on all the time. I know each of the hero's abilities but it's still not always apparent what he's doing at any given time. Demented Shaman's slow in HoN has a constricting vine effect, his heal is heal-colored and the visual bounce is clearer,
etc..
I do really like the stash interface for picking up items, but there is no way or at least no clear way to use it for storage without anything in it already. Why does the outpost have two pages instead of a scroll? I don't like the regular shop at all either but I'm willing to chalk that up to familiarity.
There's plenty of good in DotA 2 visuals, but the combination of the input delay and lack of good spell feedback in most cases makes it awkward to play. I played a bunch of it (and still do occasionally) when I wasn't playing HoN at all so it's not a switching back and forth or adjusting thing, and while it was a fun experiment, I was not very convinced. The real test for the game will be where it goes after it's finished porting DotA whole hog.