I like League of Legends, but it isn't like a traditionally MMORPG. Its a pvp based RTS. Although I like the game, I play it mostly because I have a friend who does and Sona makes me think of Hatsune Miku- like her onee-chan or (50% against/50% for) an older version of her-I truly believe that the creators of League took some inspiration from Miku to think of Sona's design: personal opinion here though. Anyway Dota/Dota 2 and League of Legends are supposedly the same type( i have a friend who played both and said so, so i have no personal knowledge) so as far as the game goes its for fun: yes there is a serious following but that's with most things that become rather popular- mainstream it may be now but I personally find the game to be rather fun: its an MMO so expect the occasional ass faced dick head.
I think the game is fine but if you're looking for an RPG game with lvling and skills an items and many enemies and sub-bosses, bosses etc.. or most other classic mechanics found in most Role Playing Games, so I don't recommend it for people who don't find pvp as a major focus, or enjoy having to restart every match.