Lately, I've only been using GM for rapid testing of C++ code when I desire a graphical interface. This leads me to believe that GM Studio will not be worth worth the anticipated price.
Really? Every game YoYo has released has been written with GameMaker (effectively very early versions of GM:Studio), and not only has it helped to fund our growth, but it helped to get us placed No.40 for the develop top 100 development studios (
LINK), get games featured on a regular basis, and now has YoYo up for a Best Publisher award (
LINK)!
We've never said you'll be writing the next Unreal, but I think we've proven over and over again what IS possible, and if your dedicated and smart, just how well you can do from it.
Having used Studio properly to make a game (not the early ones for most of YoYo's previous games), I have to say I love it! Being able to see, and develop your game on the device is amazingly cool.
...............although I would say that. All I'll say, is just wait. We have some really exciting news that'll have you all drooling!

EDIT: Oh, and as a cool little "aside".... GameMaker:Studio will have Box2D Physics across the board - and that's not even the exciting news!