This project is really interesting to me, but my biggest issue is the code completion issue. I can deal with writing UI code manually, but Cocoa's APIs are complicated and I find it difficult to remember the method names, argument names, etc. Ruby's nicer array and dictionary syntax may make that easier though (alleviating the need for [NSArray arrayWithObjects:...], [NSDictionary dictionaryWithBlahblah] and replacing it with simply [] and {} to remove complexity.)