I tried it and can't stand it.... LoL > Dota 2
Personal preference. LoL is more casual than Dota 2.
Now then, to OPs question: This game has a HUUUUUUUUUUGE learning curve. And I mean HUGE, in order for you to be effective at the game, you need to atleast play every single hero once, so you can egt an idea on what they do.
You also need to learn what every item does, how they work, and what works well with other heroes. This game also punishes you. Alot. If you die, you lose gold, if you're too slow, the enemy will deny your creeps, if you dont work together with your team, chances are you will lose.
But once you get an understanding of the game, know what to do, how to last hit, how lane setup works, how to counter pick, etc. etc. It becomes a very rewarding experience. Winning a game where you and your friends beat the enemy team in a fair match, its the greatest feeling.
Try it man, if you have the time and patience give it a go.