Prior to a brilliant career in action, Keanu Reeves started out in comedies, quite a good one by the way, I also advise you to read 'Last Night' (1988).
Of course it's just a light fun movie and you don't have to look for anything special in it - just relax and enjoy hilarious gags and amazing music, which I would call the main feature of the movie.
In general, the theme of adaptation of people from different historical periods was very popular then, remembering the same French 'Aliens', in the animation of examples, of course, will be much more and of course, the main goal is simply to introduce us to historical figures, rather than to penetrate into the depths, for which the authors and here too often resort to templates. But, it was a very good idea to bypass some offensive templates - Napoleon is not such a dwarf, Joan of Arc is quite cute, and Sigmund Freud is not concerned, and just a nerd. I don't know if that's true historically, but I like it better.
As for the acting game, of course, everything here is nothing more than the implementation of images, that is, despite the fact that actors are unlikely to bring something of their own in their characters, but at least look quite natural and appropriate, that is more than success, if you take into account the purely entertaining goals of the film.
But the performance then succeeded - funny and bright, very memorable, of course, not without joints. Therefore, if you did not like the film - most likely you just expected too much from him, it is absurd to consider this film historically accurate or even serious.