I think if you know OOP you will be fine. The synthax is not usual as most programming languages though, e.g.
object.function(var arg1)
looks like
[object function[var:arg1]]
if I remember correctly.
If you have an Apple Dev ID and iTunes, you could go to http://developer.apple.com/iphone/index.action then go to the Getting Started videos (after which it should ask your Apple Dev ID at some point then launch iTunes). There you have a bunch of videos. The one called "Introduction to Objective-C and Cocoa Touch" can be a good start to look at.
Hope that helps.