Amalur decided that they didn't want to go for a 'realistic' look -- instead, they let Todd McFarlane (of comic book fame) do the character designs. They're quite detailed (and as usual, you can customise the looks of your character quite a bit), but they're kinda... cartoony. Which is good, because it avoids the whole uncanny valley-thing that Skyrim has going on. Same with the environments: very colorful, detailed and lush.
The background is pretty detailed as well. "Epic" doesn't even begin to describe the main questline -- the backdrop is a war between the immortal Fae and the mortal races. The various factions are well-crafted as well. It all makes sense, and as you gradually learn more about the world, it all fits together. I especially liked the Court of Ballads questline, because it gives a very interesting look into how the Fae deal with their immortality. That's some inspired stuff!
The side quests are amusing. Sure, there's the usual "go there and take that, bring it back to me"-type of quest, but there are also many dungeon crawls included. And in some areas, there are mini-questlines that you gradually unlock, unfolding a cool story of it's own.
Combat is action-oriented, like it's a fighting game. You press buttons, time your attacks, jump around, use a bow... A nice break from the tactical, 'realistic' combat in Skyrim and Oblivion.
I'm about 33 hours into the game, and I'm not getting bored yet. It's 'lightweight' in the sense that it's not all dark and foreboding. And since the studio that created the game has gone bankrupt (it wasn't the big hit they thought it would be), the game is getting cheaper all the time. It can be had for under EUR 30 new, and even less than that second hand.