Well, I can't say it isn't interesting.
At PAX East, I got the opportunity to play Heroes of Ruin with fellow staffer Jon Lindemann (read his impressions here). Since he already covered the basics, I figured I would talk about my co-op experience and the game’s dungeon crawling.
As an action RPG, Heroes of Ruin attempts to take a well-established genre and add some twists to change up the experience, and from what I've played, n-Space and Square Enix has been somewhat successful. One particular difference comes in the game’s randomization of dungeons. With the exception of things like boss rooms and areas relevant to quests (which, even then, have some random locations), every experience in a given dungeon is slightly different each time. I think this is kind of cool, but I am also troubled by the idea, as many games utilizing a random format tend to make the experience feel less valuable. Thankfully, the forest dungeon I played was well put together.

Within these dungeons, there are NPCs offering side quests—alongside an overarching quest—requiring completion (in this case, it was beating a boss). For instance, one quest had Jon and I collecting materials scattered inside the area. Obtaining the items provided a stronger weapon than the basic one offered at the beginning of the demo. With this tool equipped, some particularly challenging fights became quite a bit easier, though collaboration was still required.
I used the Vindicator, a warrior class built for melee combat (as opposed to Jon, who played as the Gunslinger, with focus on long range). I had basic sword slash, as well as a special move (a forward dash). You can map to three of these special moves (which have limited use) at once to three of the face buttons, with one reserved for the basic move.
As the warrior class, the experience was quite traditional, though I feel like my time with the game was somewhat less enjoyable because of that fact. With all the special moves unlockable through leveling up, I presume playing will become far more interesting once I get to play with the skills a bit. As it stands, though, I would be lying if I said the Vindicator experience didn't feel a tad generic.

As a dungeon crawler, I was very impressed with the exploration, something often limited in games of the genre. Alongside monster fighting, there are the aforementioned side quests, plenty of secrets (Jon and I found ourselves in front of a slightly hidden spot, where cutting some branches led to a room filled with treasure), and even some really clever puzzles.
Co-op is clearly a strong aspect of Heroes of Ruin. In addition to the option for voice chat in online co-op, the game carries some subtle examples of the value of playing with someone else. Simply put, this game requires communication. Jon and I had some really good back and forths about things like what quest we should be focusing on, whether the other needs help, and general strategy.
The difficulty of going it alone is another reason to play cooperatively. When Jon and I were separated, I noticed I was rushing through potions much quicker than I would be if we were fighting together. For the brief chance I had to take on the boss of the dungeon, fighting solo was absolutely impossible, and it felt like I was dealing a fraction of what I should be (which makes sense, since this is intended as a four player game). Like many similar games, much of the fun comes from cooperating with one another, so much so that I don't think the game would be especially fun as a solo venture.
Heroes of Ruin is definitely a game I'll keep my eyes on. Although a design choice or two were questionable, the opportunity I had to play this game gave me faith that something of this magnitude can be done on 3DS, something I was not so sure of coming in.