I am still using my late 2008 MBP. I cannot shut it down due to a cold solder joint. I have to take a heat gun to the logic board to power it back up. Even with that pain, I refuse to upgrade since you can't upgrade memory or SSD on the newer units. Apple has lost it.
FWIW ours (the 2008) were crippled when new, limited to 6GB of RAM, then later they released a firmware update to support 8GB. My new Retina has double that, and honestly has plenty of memory left even when I am editing graphics while video is rendering in the background.
And you can upgrade the SSD on these models, it just isn't a standard 2.5 drive which is quite frankly a dated form factor. The upgrades are more expensive however.