With Tuesdays announcement I was so disappointed with what Apple had done to the iMac line, specifically the 21.5'' model, I went out and bought the previous generation from Stormfront in York.
The new 2012 21.5'' model has been made substantially worse. It has a much slower 5400RPM hard drive, no user upgradable ram, but the biggest nail in the coffin for me was the lack of an optical drive. Apple also had the cheek to charge £99 more for the new one over the previous model. I shoot wedding photography and am currently in the process of archiving old family VHS tapes onto DVD so an optical drive is a must, the lack of FireWire on the new ones is also a bit annoying. I know you can buy an external optical disk drive and thunderbolt firewire adaptor, but why should I even need to? Especially for a desktop machine, making it thin is as pointless as a chocolate fireguard.
The iMac I went for was the basic spec 2.5Ghz and its a million times faster than the old 2.53Ghz C2D in my MBP. I'm intending soon to put in 32GB RAM and i'll be all set. Maybe a external thunderbolt drive when costs come down too.