No I've never played DoTA 2 before. I know you have to kill towers and stuff. And you have to be miserly with your food or something.
its like a schizophrenic mix of tower defense and a PvP centric MMO, start at level 1 each game and they last 30 minutes on average
RTS controls, but you only have one unit. So it kind of controls like Diablo or something as well, for a source of reference.
Tons of shit you need to learn about game mechanics, but when you start everyone is equally as bad. Worth playing if you don't mind a skill curve and enjoy reading about a game to get better at it. Lots of guides on youtube or "commentaries" where people play a hero and describe what they do, very good way of learning.
If you just jump in and don't know anything, you will probably get confused and rage and uninstall the game, unless you have decent RTS or MMO pvp experience, but skills in both are needed.
Over 100 heroes, all available at the start to you, each with 4-6 abilities, and hundreds of items. Games are a 5 vs 5, so it means every game has limitless, unique possibilities in how they play out. So at first its confusing, and guides are your best friend on what is good to buy or level first. Once you get better, you will be impressed by the depth of the game, and if you have some friends it is easily the most fun (and rage inducing) team game to play.