After the first season...
...I think it is possible to make a fair judgement concerning the show.
Question 1: Is it a good TV show?
It depends. If you have been living under a rock and never seen a CBS show before, you might be enthralled by the twisted storylines. If you have been an avid watcher of CBS in the last years, you might get the feeling that you have seen the episodes before and be bored pretty fast because of the than very predictable storylines. If you are still watching shows like The Mentalist and Castle and can't get enough of the kind of stuff you might enjoy it nevertheless.
Question 2: Is it revolutionary TV?
The show is often praised being a flagship for gender-equality (with only one woman in an entirely male cast?) or minorities in general. Don't expect too much from it. You'll have more luck to find a compelling minority character with actual storylines in any USA Network show than in this one. Elementary is more or less standard TV level, and can go just as easy wrong as any other show. Personally, I don't want to see another episode about Asian sex-slaves from CBS ever again.
Visually, it has it's moments, but again, there are other shows who do what Elementary does much better. It's just standard fare.
Question 3: Is it a good Sherlock Holmes adaptation?
No, it isn't. There are two kinds of adaptions, the ones which really try to adapt canon, and the ones which only work with the concept. Elementary falls mostly in the latter category, but there is really not much left of Sherlock Holmes. Different era, different setting, different characters with different backstories...there are a couple of nods to canon, but Elementary even gets the references wrong. In one episode Holmes refers to a "problem at Thor bridge" during which he entered a crypt, but the canon scene with the crypt happens in an entirely different story. One of the few episodes which is actually based on an existing story is the one in which Milverton turns up, but it is adapted without any understanding for the source text.
In conclusion: If you watch everything which has the Holmes name on it or if you really, really like Crime Shows, or are a fan of any of the actors, you might like this. Otherwise, don't bother. There are way better adaptations out there.