Not a huge fan of the game, and I played DOTA back on WC3.
I find it rather one dimensional. It's all micro with very little variance in strategy. The way the meta works everyone plays the same every game... not to mention there's really only one map that's used. I got bored pretty quickly.
When you factor in the (crappy) community.... I'm quite amazed it's as popular as it is.
On the plus side, Riot made out like a bandit with this one -- there's not a lot of a content needed (one map, the same spawns and units, and some champions), so there only needs to be small teams for balancing and introducing new items/champions for the stores. The dev cost should have been much lower than other games, and the F2P model is clearly working for them.