The 2009 Macbook Pro I find feels more solid without that flimsy battery hatch on the 2008 machine. The display is also light years ahead in terms of viewing angles, color and the general look of images, text and webpages. The battery is obviously superior. I found it charged much faster after running it down for the first calibration. Obviously the addition of the extra ports, like SD and Firewire are an added bonus.
Personally, I'm inclined to just update every 12 months and sell the old machine. These machines hold their value so well and so far the updates have been worth the few hundred it cost me to update. I personally wouldn't waste my money on the higher configuration. The entry level machine holds its value much better, and there's no real world difference between the processor speeds. Also, I had Apple Care on the 2008 and it really isn't worth it in terms of resale, although I bought mine pretty cheap on eBay.
I'm loving this new machine. Apple is on a serious roll with the Macbook Pro. There isn't a computer out there in this price point that comes anywhere close to it. I give it 5 puppies.