I haven't seen Elementary yet, but the British Sherlock is definitely not canon. For that matter, I suppose Elementary isn't either since both shows transport Sherlock and Watson to modern times. I don't particularly care for how they portray Watson, but I enjoy the show and just roll with the changes.

I have the DVDs of Sherlock seasons one and two and insisted that my husband watch them. He was seriously unimpressed. He definitely prefers the movies starring Basil Rathbone and Nigel Bruce.