No reason not to buy it if that's what you're interested in.
About mid-way in the product cycle (released in June, and typically about a year between new models).
I was always a fan of the iMac, but eventually I realized that I could get the same power in a laptop (MacBook Pro) for a somewhat similar price. I use the MacBook at home with a cheap larger display monitor and it's the same as having a desktop. On the rare occasions when I want to bring it with me on a trip, it's easy.
Starting price is $1,300 for the iMac, MacBook and MacBook Pro
I would recommend looking carefully at the specs, deciding exactly how you'll use it, and buying accordingly.
I've been a Mac user since 1987, I used to w*rk for a custom Mac software developer, and I've been a consultant on contract to Apple, so I'm clearly biased.
OTOH, I've also developed custom software for Windows and UNIX, so I have a pretty good perspective. But I always come back to Apple.