And this is before you've added the wealth of tactical factors that being a team game adds into the equation. Working in pairs, threes, fours, launching ambushes and then retreating, all of you pushing a single 'Lane' of towers and minions simultaneously before returning to your posts, and how to react when the other team tries any of this.
You've also got the consistently fun experimentation of not just playing different Champions (which might range from an archer to a tank to someone who specialises in turrets or time or poison or healing) but seeing how different Champions work with other Champions. And all of it is executed with such incredible polish and attention to balance. To say League of Legends stands up to high-level play is to say fire is, perhaps, hot.
All this said, that incident with the stir-fry and the rain? I did quit the match. I abandoned my team and all that XP. Because while League of Legends is free, and brilliant, and really fun, it's still a touch disposable.
Because Riot Games doesn't want to give too much of an advantage to veteran players, the Summoner System only ever lets you tinker with tiny percentile buffs. The difference between a level-1 Summoner's Champion and that of a level-15 might be visible, but the difference between whatever level you are and the next level is not. Also, Riot Games' supreme vision of DOTA is somewhat unfinished right now. Plans for many different maps and support for clans and tournaments are currently just plans.
Finally, and DOTA fans won't like to hear this, there are still a few problems with this game. Screwing up early in a match doesn't just cost you that match, it can often render the remaining 15-20 minutes of it utterly miserable. Higher-level heroes can not only kick your ass, but because they don't have to hide they have an easier time gathering experience, making it almost impossible for you to close the gap.
This sad inevitability is just as bad when it's your whole team that's even slightly outclassed by the opposition. Thanks to all those rock-hard towers the other team have to break down, few games offer so slow a defeat as DOTA. LOL tries a few things to fix this, like giving you the chance to initiate a vote for team surrender when all is absolutely lost, but use of it is highly restricted.
But there's not much room for negativity here. More time, heart and money has gone into this than any other free game I can remember playing, and I think Riot Games is going to make good on its promise of post-release development. Until further notice, this is the DOTA game you should be playing.
You can play League of Legends now, for free, at the League of Legends website.