Warrany = Insurance... They are sold because they make money for the people selling it.
Do you plan on having enough disposable cash lying around to handle any issue that comes up? If you are - then you are less likely to need the "insurance."
I bought a used Blazer a few years ago, and was offered a 3rd party warranty for free (dealer was brand new and trying to make a name for himself). EVERYTHING that failed on that car in the first 3 months was NOT covered in the warranty. Read the doc carefully, as you did not say this was a Subaru warranty. Most 3rd party warranties are VERY specific to certain engine and transmission components and nothing else.
For instance, the fails on my blazer that were not covered by the engine/transmission warranty:
- CEL light constantly on.. I personally had to replace the CPU, and all 3 O2 sensors and could still not make it go off.
- Exhaust manifold cracked
- 4X4 locking intermittent
- Gas tank rusted off. Yes - off!
This is why I now own a japanese car...
Good luck with your WRX! I love mine. Don't worry about what you paid for it - that is behind you and its just time to love the Subi.