@crysack: I tend to agree. My friends religiously play vs. AI matches once to learn a new champion in League, whereas I look up the kit and then go play a PvP game because the champions really aren't that hard to play. There's a fair amount of variety in play styles in champion design, but the kits themselves tend to wash together a little.
While more recently, Riot has been putting work into more interesting design (Braum, Yasuo, and Vel'Koz to an extent). This, however, is why I like League's game design better: you don't have to spend time learning the intricacies of the champions because League isn't about the champions, it's about the flow of the match.
There are no denies in League, so instead you focus on controlling the lane through zoning with damage and vision. Inhibitors can respawn, so attack and defense strategies can change depending on that timer; turrets are a much bigger threat earlier on in a League match than a Dota 2 match (and it seems like Riot's intending to make them a bigger threat next patch), and there is no backdoor protection on League towers. This isn't to say that Dota 2 doesn't have its own intricacies that change the match flow (ex: time of day or destroyable terrain/trees), but League feels like it was designed around its systems first and foremost while still remaining penetrable.