They have an "item shop". Not sure about ingame ads. I played the game for 5hrs last week and didn't notice any, so if there are any they are decent.

Oh, micro purchases, got you. Do people do that much?  Can you complete the game without them?

I really am lost on phone (and should add browser) games with their economic model.

You can't complete this game. It's an endless runner.

They just save you some time for unlocking useless upgrades, so yes: You can (as far as you can call it "completition) "complete" the game without them. They don't unlock a magical barrier that stops your running or anything like that^^

The micro-purchases are optional and something like 90% of people don't buy them, but the percentage that does, ends up buying quite a bit.

There might be ads, I dunno, and I was playing it a couple hours ago.  lol.  If there are they don't detract from the game obviously.

Downloaded, and still have to play it. It does look more varied than the first game.

My friend downloaded it the other day, I'll get it once it hits Android, my high score on temple run 1 was around 5 million I think, so I'm going to try to beat that :D

Pretty impressive bearing in mind it's only on iOS at the moment - it deserves it though its a pretty addictive game 

my high scores are 2.5mil on the 1st and 1.5mil on the second but the second is harder I think

That's basically all it is. Though the graphics are way more interesting to look at. 

I downloaded it, but haven't played it yet.