I'll start by answering the question and then go off-topic
I don't think DRS is dangerous, even if it fails like in Michaels case. Sure, when it stays open when you don't expect it, it will be unexpected, but I can't imagine the driver not noticing it even during braking. Considering there are very few high-speed corners with walls directly behind the braking points, the risk of a serious accident is quite small in my opinion, as drivers can always brake more and use the run-off or come to a (near) stand-still. For me, it is the same as worrying about steering failures or tyre failures. A tyre may fall off, the steering may fail, but the chance of it being very dangerous is not high enough to ban it. It is a case to discuss, but in my view not a reason to ban just yet.
I'm not convinced by the use of it. It doesn't feel right. It's a solution for a problem that shouldn't exist in the first place. I do think the FIA secretly knows it, the DRS hasn't been all that effective, Lewis would've gone past Alonso and Vettel anyhow, with or without DRS, but that same DRS spoils those moves as the drivers are clearly waiting for it. I understand the difference between impossible to overtake and cruising past is tiny, and it is that difference we are looking for, but I don't think DRS is the answer to get to that point.
I have to say, I'm really enjoying the post-race analysis by Sky F1 (which I'm watching now), with a honest discussion about DRS, current racing and the merits and demerits of it. Thanks to Sky F1 for a brilliant show all-round this weekend and especially for allowing an interesting discussion that is quite critical of the state of the sport they are just beginning to broadcast, very refreshing (no, I'm not a Sky employee