The only major spoiler to watching out of order (which I did by the way) is that the jeopardy where John gets abducted by Mycroft in the first episode is neutralised. If you've never seen Mycroft, you can fully appreciate how intense that situation might have been for John. Unfortunately, by the time I saw the first episode, I already knew who Mycroft was and was not freaked out by the warehouse scene at all. I get that they were trying to make him into a mayby-moriarty but since I already knew his identity, I found the scene more funny than anything else 
Last edited by saturnR (June 22, 2014 7:40 am)