Last week we had a session with Bart who did a great job explaining SDL Tridion in the way implementers see it.
However, this meeting left me with a feeling that XSLT is one of the misused and misunderstood tools which is not popular with developers or implementers. Probably because it requires a bit more knowledge to be applied successfully.
CME supports XSLT extensibility and the mechanism itself is relatively simple. It allows you to include your own XSL transformations at the top or at the bottom of extending XSLT file.