I like the basic last hit mechanic and see the logical progression to denying creeps (though I'm not a huge fan of it). It does make the laning phase a little more interesting in solo lanes at any rate, but I just don't value the mechanic. I'm still a fan of last hitting though. I don't think lol is a dumbed down dota though... at all. I can't think of that many things that are wildly different from lol in dota1-2.
All of that said - could I get into dota2? Sure. Do I currently have any desire to do so? Nah. LoL has the most coverage that I'm aware of. Plenty of cash tourneys and worldwide ones as well. Riot's been doing this for a bit. Value is quite new to the game and honestly, as of today, doesn't have enough staff dedicated to make Dota2 a success. Folks will play it and like it, but if valve doesn't decide to dedicate a larger team to additional content, steady patches, and getting sponsors and tourneys going... well, lol will be around in a few years... and dota2 will be the next demigod. and ALL of that said - all it would take is for valve to dedicate a sizable staff and decide to get serious about competing. Will they do that, though...