That isn't much different from any transition into any new platform. Whether you'll want to go to Windows, Linux, Android, Java, etc. there are a number of frameworks you'll have to get familiar with. The language is usually the least of this. Good developers can do the transition fairly easily and do so a number of times in their career. That doesn't really tell you anything about the tools.
The XCode tools are pretty good but they feel a bit old to me. I've done a lot of Java development and XCode doesn't really stack up well against Eclipse or IntelliJ Idea, which I prefer. It feels like going 10 years back in time, and the Objective C syntax seems decidedly archaic although the features of the language aren't bad. I'd much rather use Ruby, which is similar in spirit to Objective C but with a much nicer syntax. Also, closures and properties were a part of Ruby from the start whereas they've been added on later on Objective C (and it shows). In fact, closures haven't made it to the iPhone scene yet but I've read that they'll be part of iOS 4.
You should try some other tools just for the fun of it. Builds character. Familiarity is part of it, of course, but Apple could take a few pointers from Visual Studio, Eclipse, and Idea. I was actually surprised that you have to build the code before getting error messages in Xcode. That's so last millennium
I think that Apple should apply their own philosophy on their tools and their language. Modernize Xcode and use a nice, statically typed, multiparadigm language with loads of sugar and a garbage collector such as a Scala variant. Now THAT would be awesome.
Or at least give people the option of building compilers for such languages. Apple may fear other languages and other tools but they are effectively hampering the innovation themselves.
Not gonna happen, I know
That being said, I get their stance on Flash but the collateral damage is significant.