I'd only seen this movie once before, when I was about 12 or 13. It wasn't as good as I remembered it as being but still better than 80-90% of the kids' movies these day. I've seen quite a few Holmes films and, in my opinion, the performances of and chemistry between whoever is playing Holmes and Watson is what largely determines the success or failure of the movie. I'm glad to say that Nicholas Rowe and Alan Cox (son of Brian) were both excellent in their roles and the development of their relationship is nicely handled. It's such a shame that this didn't lead to bigger and better roles for either of them.
Rowe and Cox (and the script, of course) made younger versions of two of the most iconic characters in all of literature credible as teenagers while still more or less staying true to the spirit of the characters in Holmes canon. So often where you get younger versions of established characters, it doesn't work but this is a definite exception. The story is not as strong or as tight as it could have been and occasionally veers a bit too much into Indiana Jones territory (unsurprisingly) for my tastes but, hey, it works in the context of the film which is the main thing. A sequel would have been nice but, alas, it wasn't to be.