Would you consider the Space Shuttle a failure?

Yes and no. During Apollo we landed on the moon multiple times with no fatalities except Apollo 1 on the launch pad. The Shuttle had two accidents while in flight.

It's a hard question.

I suggest reading this book before you proclaim it a total failure...

Space Shuttle: The History of the National Space Transportation System The First 100 Missions, 3rd Edition [Hardcover]
http://www.amazon.com/Space-Shuttle-National-Transportation-Missions/d p/0963397451/

It's a tough one to judge, true it never lived up to its initial promise, but does that automatically make it a failure?
It's probably hard to say what history will record it as.

Like so many other things in life, the answer is complicated. Yes, I would say the STS was a failure in that it was much too expensive, too complicated, and too dangerous. It was misguided. Too many compromises. It tried to do too many different things which weren't quite compatible.

On the other hand it was a great technical achievement in many ways, and I'm sure much was learned from the program.

Ultimately, I believe the U.S. space program would've been better served if we stuck with the Saturn V and Saturn IB rockets for manned missions. We should've continued to refine and improve them. (And of course we've got a stash of smaller unmanned rockets: Atlas, the various Deltas, and now Falcon 9, etc.)

Skylab was an awesome space station. Wouldn't we have been better off with multiple Skylabs rather than one big and very expensive ISS?

And now with the forthcoming SLS I see plenty more nonsense. A big expensive mess of a program without a solid vision and plan. And every time I read "shuttle derived" in regards to the design components I get annoyed. Rather than building the best possible rocket for the money engineers are being forced to compromise in order to keep certain aerospace companies in business. Ugh.

Here's hoping for another Space Race to get things really moving...