We are at a crossroad as what development tool to use for our application. We do not know if we will go for Adobe Air or use the traditional road which is Objective-C and Cocoa. The software is similar to www.riffmasterpro in functionality. Is Air the best solution here?
If you're looking to build an app solely for the Mac/iPhone platform, I would suggest using Objective-C instead. Adobe AIR's strength is that it can be installed and used cross-platform with little problem.
One of the downsides of that, though, is that performance will never be as good as something that ties directly into the operation system.
Well, firstly, Flash isn't supported on iPhone so there is no Air platform for iPhone (at least, none that I know of - correct me if I'm wrong).
Secondly, native Objective-C applications on Mac will always surpass Air applications with regards to how well they tie into the OS. An example of this is TweetDeck. It's an amazing application but it just doesn't feel like a Mac app (no meaningful menus, no growl integration, etc...). Mac users are typically very specific with regards to how their apps behave.
I would advise that if you want to write Mac applications (and iPhone applications) to rather stick with Objective-C.
If your primary concern is cross-platform (with the exception of iPhone) then Air is an option worth considering.
problem of using middle frameworks is that you will never have the potential of the hardware, in other worlds you will not be able to use any feature that Mac/Windows can give to you by the hardware, you wll always be attached to what the framework will give to you and hope that you can do everything that you need...
specially in your music application.
regarding the Adobe Air framework, it is a good idea to cover both Linux, Mac and Windows computers but you will not be able to run it under the iPhone because there is no Adobe Flash supported... Adobe is making a flash player for the iPhone, but I do believe that will ot support Air, at least by the near future.
For the iPhone you can build a Web Application or a SDK Application, the last on, and if you will use SDK 3.0, you will find plenty of good things to use it to, but you need to develop a full application from sctrath.