If you've spent any time at all on GD, you probably remember the thread I made about it there. That was before I'd played more than a few minutes of it - long enough to tell a few things about the interface and the fluff, and not much else. This review was written with the benefit of perspective, so hopefully if you remember that thread, you'll read the whole thing (or at least most of it) before you claim that I'm talking out of my ass.
Dota 2 is, without a doubt, the hardest game I have ever played. In 13 years of experience, nothing comes close to this (at least not in terms of difficulty.)
I'm not exaggerating. This is a seriously hard game, especially since Valve hasn't finished any new player tools (such as the tutorial or the mentor system from Team Fortress 2) yet. The game also hasn't been properly released, so the only people spending $30 on an invite (which can only be done from inside the game) would be people who love the game and want either their alternate account or their noob friend (most likely also taught by them) to have the game too. And even if you do have a friend willing to teach you the game, do not expect to get anywhere in your first few games - regardless of how much you play any other game in the genre.
The brutality begins right from the start of your first game - the picking interface could honestly be a lot better. And I know that it's possible to change from the scrolling list to a 'grid' system, but it goes back to the scrolling list between games. And since you can't go back to list form once you're in grid form, why not just completely remove the list? It was baffling design decisions like that that initially turned me off the game.
That said, it only gets even more complex once you get into the actual gameplay. If you've ever played another LPG (lane pushing game; it makes more sense than MOBA or Action-RTS) then you should understand the basic flow of the game. Here's the thing, though: this game will punish every single slip-up you or any of your teammates make. The shop is also a lot more complex - you lose gold when you die (part of how you get punished), so you can buy items while away from the fountain which are then added to your 'stash'. The courier, if you have it, can take items in your stash over to you. There are also some 'secret shops' scattered around the map which you have to have a spare inventory slot to use, since the secret shops aren't connected to your stash, and you have to pick the right moment to go to them or else you'll get ganked in the jungle or lose your lane and AAAAAAAARRRGH
Don't rely on your teammates to help out, either. Since all five 'heroes' are controlled by separate people, often their agendas won't involve occasionally leaving their lane to put pressure on yours, warding or checking the river for runes. They'll also probably wind up picking heroes which are well out of their league.[footnote]Pun completely unintended, I swear.[/footnote] There honestly aren't a lot of 'easy' heroes, that is heroes you can be competent with without having played them to death before - Valve does have a list of them, but you only get to see it if you admitted you weren't very good on your first boot. And I didn't.
So, yeah, a lot of the difficulty comes from working out and memorising exactly what's possible with who and how to get the most out of everything. And that's definitely not something that everyone can do. I get the feeling that when the game's officially released, regardless of stuff like tutorials and mentors, a lot of people who start playing will give up in frustration. If you're willing to stick with the game, though, eventually you will figure out enough to be useful to a team at 'pub' level. And after that, who knows?
As for non-gameplay stuff, the more adaptive music is actually pretty good and while some of the voices or the things they say can get grating, for the most part it's not that bad. The interface could be better but doesn't take too long to get a handle on, and the in-game graphics are certainly a lot better than what LoL has. So if all you really care about in a game is graphics, then you probably shouldn't be playing Dota 2 anyway - as for everyone else[footnote]By 'everyone else' I mean 'everyone patient or masochistic enough to play more than a few games'. Which includes me, though I don't know whether it's patience or masochism that keeps me playing.[/footnote], they're a nice bonus to a well-above-average package.
This is quite possibly the most-viewed review I ever wrote. Probably because Dota 2 is still relevant and everything else I wrote a review for wasn't. Don't bug me about links to those reviews, because I haven't been keeping them - I'm not famous or prolific enough for that, the way Marter is. (Nothing against her, BTW.)
