Well, the Rathbone version wasn't exactly canon, either, but so many people are accustomed to it that it seems canon. (Nigel Bruce was much too old for Watson, for one thing.) The one that's truest to Doyle is the Jeremy Brett BBC version from the 80's - that one is incredibly faithful to the original stories, and wonderfully acted and produced, to boot. Brett did a fantastic job striking the right balance between Holmes's knowledge of his own superiority and his fastidious courtesy and sympathetic ear. (Watson makes a point of mentioning that several times in the original stories - after all, how could Holmes have been so popular as a private detective, especially for people with delicate or scandalous problems, if he'd been a raging asshole?)

Elementary is doing some very off-canon things, but in my opinion, what matter most is whether it's a good show, whether it treats the characters it creates with respect and organic fidelity, than whether it hews to canon. I've never been a purist of any stripe, in any fandom, so what's done with Watson and Gregson and Adler and Moriarity - for that matter, with Holmes himself - just has to make sense and catch my sympathy and interest, and I'm happy. :)