03 Golf

Have the opportunity to acquire an '03 Golf for relatively cheap. It used to be my gf's cousin's car and has sat at her aunt's for a couple years now. Her cousin says it needs a new wiring harness and that they can get it running with a jump start but it wont hold a charge.
I'm pretty handy and can do most mechanic work on my own, but I know very little about diesel engines, and/or German cars. I believe it is at around the 200k miles mark, M/T and has had the timing belt(or chain) replaced in at least the last 50K miles.
Is this something worth getting myself into? What can I expect as far as maintenance with these little cars? From what I have read, the ALH has been praised for it's reliability but what do the redditors have to say?