Nothing wrong with a Mac...
except (for me),
I like to upgrade frequently (without buying a new computer).
Many of my favorite programs (including FS9) are not available for the Mac.
High price of components due to single source.
High price of hardware/software for the Mac.
For some, it is a fine piece of equipment...although a bit overpriced.
I have been working on macs, since '95 and have found that they last longer software and hardware-wise (with a few exceptions). School labs full of macs last for years even after that much abuse and they push them to the extremes.