I enjoyed it. Ripping on incomprehensible plot mechanics in a film like this would make sense if I didn't have immediate experience reading Edgar Wallace pulp mysteries and the work of Shane Black (and a lot of shit in between)*. Kiss Kiss, Bang Bang sort of immediately came to mind in that the central mystery is convoluted and unimportant outside of bringing the leads together, as they generally are in everything Black has written (and of course, b/c of Downey Jr). What Black is really wanting to get at, by way of Chandler, are the character interactions, chiefly between two male protagonists w/ disparate personalities, and how they eventually come to find common ground, admiration, and friendship. I mean, I can't even really remember what Corbin Bernsen was trying to do, or why an actor would be all henchmanned-up like Lex Luthor, but it didn't matter, b/c like Black, I didn't care about him, I was watching Downey and Kilmer absolutely kill every scene they were in. Fucking no one compliments the actual plot of Kiss Kiss, Bang Bang.
In these Sherlock Holmes films, it's effectively the same thing. We are not meant to be able to piece any of Holmes' observations together on our own. Like many other stories featuring a detective of preternatural competence, we know nothing until they illuminate it for us. The (action blockbuster) adjustment in these films is that Holmes' observational skills are generally used as lead-ins or enhancements to Rube Goldbergian setpieces. Watching Holmes take tactical advantage of offensive and defensive nooks in his environment. I think they work quite well because of the tactile sense of place that these films get from their absolutely wonderful production design.
This sequel benefits from the leftover chemistry of Downey and Law from the first picture, and a goddamn excellent villain. It doesn't matter that Moriarty isn't especially deep in terms of motive. Arthur Conan Doyle's insertion of Moriarty into Holmes' universe wasn't anything he was building to, he was just tired of writing Holmes stories and needed some character that could conceivably be the perfect final foil for a creation that had become cumbersome. I don't think it's a coincidence that the story that Doyle had hoped would finally be Holmes' last was titled "The Final Problem". I loved every moment Harris was on screen, and though you knew Holmes would triumph, and I knew fairly specifically where and how they would have their climactic battle, it was great watching the deceptively polite, intellectual fencing match between these two iconic characters.
Noomi Rapace? It's a good performance, technically speaking, but her character is a plot device and nothing more. Done and done. Rachel McAdams? She's the Rachel Dawes of these films, she's meant to give the emotionally reserved, hard-to-know, and virtually sexless hero a very personal investment for taking on the villain. Frankly, I liked how Holmes' reaction to her death was played. He's obviously devastated, but once the news is processed, it's totally repressed and he, as they say, just cracks on with it, as does the film. If anything, that's a fairly spot on handling of the Doyle's character.
*I will admit that in a movie so concerned with being propulsive, there's a lot of incongruity when they do observational call backs to stuff like "the twins". It all happens so fast that there's never really any clever deceit or sleight-of-hand in the writing, which can come off as pretty lazy.