Some older homes have not been maintained well and will require significant dollars to bring back. If you have the cash, after buying the home, to make these repairs that might not be a problem. Many people, simply do not have the cash reserves to repair and update the home, thus a newer home works well for them.
If you purchase a home warranty, you can protect yourself from many faults associated with an older home. The policy can cover a variety of repairs including AC systems, plumbing, some appliances, electrical and more. They tend to deny as many claims as possible, but if you are tough you can get them to do their job.
One of the most expensive repairs associated with an older home is the roof. Roof repair costs have skyrocketed in the past few years. My 2800 sq.ft home cost about $15,000 to re-roof by a good company this past fall.
Whether buying a new home or an older one, get a professional home inspection. In my book this is not an option. A great inspector (not all are) can help uncover the problems before you buy. Even new homes have defects so get an independent inspection on any home you consider.
That's my take on the subject. If you like knowledge, our blog site: http://www.UrbanLifeBlog.com has a lot of articles on many real estate oriented subjects and a few restaurant reviews to keep things interesting. There is no obligation to visit... just a desire to learn.
Hope this info helps a bit.