1000 ft over and 2000 ft horizontal from anything over congested areas, and 500 ft over and horizontally everywhere else. Most of these small drones don't have control range much beyond 500 ft., so if you are inside the rules there are unlikely to be conflicts with something like the Lilly.

Of course people have been flying fixed wing and helicopter electric RC models for many years which have all the same regulatory problems. Many of them big enough to easily kill you. The only thing new in drones is that they are inertially stabilized and many are GPS referenced, making them partially or wholly autonomous. And making them flyable by just about anyone without much practice, raising the probability of all kinds of issues.

Having said that, I just preordered a Lilly too . They are not alone, many competitors in that space (leashed drones) but that is the first I have ever seen which promises to be waterproof, kind of a big plus on the boat.