This is one of my favorite shows. I really enjoyed Jeremy Brett's performance as Sherlock Holmes (though I wish they did make him a little closer to age as in the stories).
The writing of the show is what makes it stand out it is closer to the original Sherlock Holmes tales and you even get to see Mycroft Holmes, who is rarely even talked about in most series. Charles Gray makes a very good Mycroft (even if he should of been a little more standoffish). I also love how they bring habits of Holmes into life, his early drug issues, he's a slob, grumpy and a lousy morning person but he can be very personable and even charming.