One of my current desktops is an Ivy Bridge i7. It isn't that fast anymore, but with 32GB of RAM, it isn't too bad. I could really use some more cores for parallel builds though. Might be time to upgrade.
My current desktop is an i7-970: first generation i7, but hexa-core. It was the first time I bought a higher-end cpu and I've never regretted that. I also got it with 24GB RAM. Since then I upgraded both the graphics card and the disk (from WD Raptor to SSD). It's still very usable: it's for personal use and fast enough for browsing, development, and some (older) games.
My current desktop is an i7-3770 Ivy Bridge as well, though admittedly I only use it for occasional gaming now and use laptops for work/browsing.