This was one of my favorites growing up. It has such a clever premise with Dr. John Watson (Kingsley) as the true "brains" behind the Holmes and Watson duo, and Sherlock Holmes (Caine) as a drunken, failed actor playing the "face" of the duo for publicity reasons.
I actually hadn't thought about it in years, but I watched it again recently and it really is worth a watch if you want to want to see what a good Sherlock Holmes comedy can be (with two multiple academy award winning actors in the leading roles).