Agree with Joel. My late-2011 17" MBP is still going strong. I swapped the 500 GB HDD for a 1 TB SSD mainly for more storage, but the speed boost was noticeable. I'm running the latest non-beta OS, it's generally stable (the exception is an occasional Aperture glitch, but since Apple isn't supporting it any more, that's not unexpected).

If the MagSafe is loose enough to fall out on its own, you might want to visit an Apple Store. IMO, it's a great feature – it's saved my Macs from tumbles several times when me or the kids trip over a cord (I killed a work-provided HP laptop that way once).

Like Joel, I also had an HDD die. That was in my 2006 17" MBP – I replaced it with the 500 GB drive from my 2011 model. Despite being two years older than my oldest kid, that 10 year-old Mac is still running fine for basic tasks like internet browsing, MS Office, etc.