Someone around here could probably give you an answer from experience. Thing is, there are one heck of a lot of Sony decks and the same can be said of Kenwood amps. It would totally depend on what you were getting.
But... for $65 dollars on a deck, I suppose you can't go wrong if you like it's features/appearance and it works.
Same can be said for the amp to a lesser extent. You could be getting a great deal (Excelon line) or an okay deal (base model).
If you don't know the model you're buying, I guess it really does come down to how much you trust your friend

Either way, $165 is not a bad deal for a deck and an amp. Good luck!