I think he's referring to some of the issues highlighted on this board such as the known radiator/transmission cooler issue, ECM relays, corrosion issues depending on where you live.
People need to keep in mind that most individuals don't go onto the internet to find information about their vehicle unless they have a problem. Hence, you will find that it at least seems like everyone is having problems with their truck.
I have a 2005 SE Premium. I have done the rad bypass as a preventative measure. I have 120000mi on my truck. And the thing is awesome. For a 100000+ mile vehicle, I have very few problems that I'd attribute to poor design (some problems due to where I live and the conditions the vehicle put into), and none that have left me on the side of the road.
Others on this board haven't been as fortunate as I have, however, I believe this to be the exception and not the rule. Also, this is something you see with all car makes. I used to be very active on the honda boards on usenet back in the day when I had my 98 civic. Same thing there.
However, redwing's advise is sound, know what you are buying, and at least try to be aware of the known issues out there. Your buying a used vehicle, and that carries risk. Knowledge can minimize that risk.
Good luck, and let us know if you have any questions!