Ive been hands on with a couple, from $75 dollars up to around $500,and they are pretty neat toys. The learning curve on them is pretty steep if your going to want to get close up shots of the roof.
I guess the first thing is define your budget and expectations. Syma makes some pretty decent quads that come in around $100 and get good budget friendly reviews. Check out youtube to get a feel what the video quality looks like and to get a general idea on limitations. Another big name is DJI which can get you 4k video and be north of $1500.
Avoid the First Person View (FPV), flying those is really difficult because you end up getting disoriented. Get some extra batteries to extend flight times and practice. Fly it on walkable roofs and see if you can spot any issues on camera, then go up and confirm with a normal inspection. I think you'll find its hard to look at video and determine issues. It's not about video quality, it's that the different perspective and camera angle don't translate well.
I was tasked, now canceled, with determining their use fullness in a emergency response to HazMat incidents and water rescue. Although I believe the potential is there and drones can be really useful, unless you fly them a lot and get use to the camera, they aren't going to be a game changer.
Wanted to say thanks as well. This thread got me to pull my Syma X5c out and try and shoot a video for you. It was totally fucked, auto gyro wouldn't engage and was basically unflyable, and when I looked into it I found out I had a knockoff. Mine was purchased through a 3rd party on Amazon so it should be good.
