I'll be interested to see what they do with this. Murakami is making it, and he does have a good track record on superhero treatments. He does, however, have a very mixed record on the rogue's gallery. Teen Titans had numerous weak, sometimes bizarre (not always bizarre for the bad, mind you) villains, like Mumbo or Control Freak. The Batman, for as good as it was, did almost none of the Bat-villains any favors. Then again, this doesn't look like anything I've seen from Murakami before, so maybe he's finding his stride with that aspect of the series.
Also, Mike is right. It is by no means out of bounds for Alfred to have a gun. There was a gun rack at Wayne Manor in the 1989 movie, and he also had one in BTAS. This is no issue for me. I'm not sure if Alred being a former secret agent is part of DC canon, or just DCAU, but if it is canon, that would also reinforce that.