I'm in the same boat. I have a 2008 model and I was waiting for the update, but I'm not too impressed. The Retina is rough around the edges. I think it will eventually become a great computer, but right now they are just starting out. I think Apple has a more long-term vision as far as specs go. They realize it's not a full solution for most people, which is why they're still selling the old MBPs and not replacing the whole lineup.
I like a lot of things about the new model, so I plan to wait for the next spec bump. However, if the Retina doesn't catch your eye, I'd go with the normal MBP. It's a good design and it's built to last. Right now your 2008 probably performs fine, so it really depends on how long you want to wait. Either way, I think you'll be happy