the windows version of unity altogether is not that good, which is mainly caused by windows being not that optimized as macos.

any pre-2.5 version of the engine was just a dream to work with on mac os, no torque and no A7 came even close to reach the flexibility, performance and the features of the engine. the 2.5 version has a few glitches, especially in the windows version, but also the mac os version got a little slower as the GUI is now completely drawn by the engine (both on win and mac os).

unity is just easy - easy to handle, easy to extend, easy to master.

this engine definately is the strongest package out there at the moment for indie developers and also larger development teams aiming at fast, multi-plattform release-cycles with lower budgets at their disposal.
the engine is cheap for getting started with it and there are no strings attached. the main competitor in this sector will most likely be the new garage games torque release, but as I checked out their first announcement I saw that the licensing model alone is just a mess.

well anyway, i will stop rambling on now. the engine won me over last year after only 2 weeks evaluation. anybody who is fed up with A7 and its limitations, problems, bugs, etc. really should spend the 200 bucks and take a look at unity.