I've been slowly moving into the Apple camp over the last few years. So far, it's the iPhone 5 and an iPad Mini. I'm really interested in the Mac book pro for Lightroom on location. They are a bit out of my price range at the moment so I'm thinking about getting a Mac Mini just for LR and converting my catalog. I haven't used an Apple computer since the Apple IIe and need to learn the ropes. I'm more excited for IOS 7
I'm a long time mac fan but I'll advise against buying a mac mini if you are planning to use it with a DSLR. Even good mac mini are average at best as soon as you have a consequent photo library and do moderate editing (aperture + nik).
On the other hand I don't think mac pro are a necessity if you're not into heavy video editing or 3d rendering. My maxed out iMac 27"mid 2012 model is breezing through all my needs while running other heavy lifting (encoding, 1080 movie running not to get bored, compressing the exports and so forth). A lower model would thus probably be adequat for non gratuitous use.
TLDR: Serious hobbyist to stills only pros = iMac.