As a developer I still see a lot of problems with the store format and restrictions. Being able to (actually allowed to) install on "any Mac you control" for non-commercial purposes is very ambiguous. It also means that you should still keep a non-store version of your App. I've seen two companies, the guys behind Pixelmater included, that have gone App Store-only.

If I'm the tech/IT guy at a local college, it's a non-commercial setting. Am I allowed to buy Keynote or Pages one time and install it on the hundreds of machines that are "in my control?"

There's no provision for site licenses and you're most definitely not allowed to implement any type of licensing restrictions/protection of your own as far as I know.

Apart from having to build two binaries and user confusion, I can't see any benefit to dropping direct sales and going exclusive with the App store. especially if a developer is currently paying less than 5% per sale for the credit card transaction and now has to end up paying Apple 30%

A lot of prices were also lowered when apps appeared on the store. Not sure if that's a permanent move or a sort of intro price. This worries me as well, I see a lot of devalued property out there.