Mostly Yes
If you're sticking to what BlitzMx is able to do and want it easy out of the box then definately Yes.
If you're having something bigger in mind, want to spend more money, want to use physics or want a 2d/3d game, target other platforms as well like Online, the iPhone and maybe consoles later on but no Linux, don't fear investing some work into setting up your own 2d framework in a 3d engine before, then No, Unity is the better option then.
If you're sticking to what BlitzMx is able to do and want it easy out of the box then definately Yes.
If you're having something bigger in mind, want to spend more money, want to use physics or want a 2d/3d game, target other platforms as well like Online, the iPhone and maybe consoles later on but no Linux, don't fear investing some work into setting up your own 2d framework in a 3d engine before, then No, Unity is the better option then.