I'll chime in with a few anecdotes of mine. We've had one in the family from new from 1990. That's 19 years and just under 450,000 kms (maybe more, but the vehicle had a broken speedo cable for two years - so I'm guessing conservatively here). Not babied, it's a 3-dr with an N/A 4D56. As far as reliability goes, if you change oil regularly and use good filters, it will NOT let you down. It's only when you neglect it is when it starts to suffer. As far as breaking timing belts and bending valves is concerned, it breaks off its rockers before it bends valves. The valves go straight vertically into the combustion chambers, so bent valves aren't really a common occurence IMO.
The engine was re-conditioned at 380,000 kms (again, an estimate) in mid-2005. Since, it has been smooth sailing. Even before being rebuilt, it was just weak, but it still ran fine. Going up mountainous roads was tough though, requiring low-range at every opportunity.
Overheating issue? Make sure your not giving the engine death. It's a diesel for heaven's sake. It's supposed to lug, not to be revved to the moon. Max torque is at 2000 RPM. I change gears before. It stays happy and cool, doesn't drink fuel, and doesn't scream. Ours started overheating in traffic (in 45+ outside temp with A/C mind you) The problem? A recalcitrant thermostat. Changed that, now is as cool as a cucumber. Redbull_ar, Ahsen_rg, Spectra, and Ghuncha will vouch for the condition of the vehicle.
P.S. Please be careful in selecting your car, if it's been abused, you might get stuck with a money pit. But if it's in good condition overall, I say go for it, you will not be disappointed. (y)