No, they're not a good car at all. My mom had one, and it was in the shop all the time even when relatively new. It was a huge piece of crap.
They're nice looking and comfortable, and drive really well when they run. The "when they run" part is key, though. That's also not to mention the fact that it leaked like a sieve, to the point where there would be an inch of water standing on the carpet when it rained, and three trips to the dealer(fortunately under warranty) couldn't fix the problem.
They handle well, but are woefully underpowered. They're a heavy car with not nearly a powerful enough engine. Cadillac really skimped by putting a V6 in-they should have had a V8.
If you want something in the same vein but that's a whole lot better, look for a Lincoln LS or Cadillac CTS. Either tops the Catera in reliability and are also a lot faster.