Isn't the Golf usually pretty reliable, though, because of it simplicity? Unlike VAG's higher spec models, there isn't a ton of stuff to go wrong with it.
And $8k for a car with less than 90 000kms is a pretty good price. And the 2.5 likely has a lot of life left in it. No direct injection to foul up the valves, no turbo to fail, just a basic, naturally-aspirated 5-cylinder (LOL)! It doesn't even have a DSG, but rather a time-tested 6-speed automatic (if not equipped with the 5-speed manual). Biggest downside to the engine is it wasn't that fuel efficient.
That being said, 90 000kms is about the time that you'll have simple things start to fail, which is totally normal. Ball Joints, tie-rod ends, struts, etc. These are all normal wear items, even more so if driven on rough roads.
Is your friend the first owner? Does he have all the maintenance history? Bonus points if both apply...
If the car is in good shape, has been well maintained, for $8k, I would go for it, if I wanted a nice little hatchback.