I joined the iPhone dev program back in August last year (subsequently released a puzzler). It didn't take a long time to get accepted, a few weeks maybe, and this was applying as an individual. If you apply as a company, the process seems much longer from what I've heard.
As for how easy it is, when I developed my puzzler there weren't really any things like Unity or iTorque available yet (I mean, they were available but there was no iPhone publishing for them), so I learnt Objective-C (I have plenty of previously programming experience) and built as I learnt. I have to say it's actually a really elegant language and if I had cause to I wouldn't be adverse to developing again for either the Mac/iPhone with Objective-C. You tend to mix in a lot of C and C++ but overall it's nicely structured and the libraries provided are fairly well documented by Apple and provide some fairly high level functionality quickly and easily.
There's also a nice library now called Cocos2d (
http://code.google.com/p/cocos2d-iphone/) for 2D game development which I've played with a bit (didn't actually use it for my puzzler, again it wasn't really in any state to use it when I was developing) and seems very useful, so that might be worth investigating as well.
Hope that helps.