I think that hval has it about right and good comments from those that have actually operated UAVs. The usual ill-informed, daily mail level comments from those that clearly never have.
UAVs can be far better than manned aircraft at many things, but they are not a panacea, manned military aviation has a good many years in it yet.
On the flight in civil airspace point, they already fly in civilian airspace in many parts of the world, but the CAA has displayed its usual proactive, forward leaning approach to new ideas so not in the UK yet (and now it's more european so not optimistic). For see and avoid, how much lookout do you think an airline pilot does in the cruise? Somewhere between zero and none? For SA, in my experience UAVs have far more SA than manned aircraft because they can get so many different feeds and they don't have to look through the soda straw!
I am referring to large scale pred / reaper type UAVs of course, not the radio control aircraft that are a completely different kettle of fish.