I drove various prototypes (though not for hours) and don't really feel much difference between their seats and the ones in my car. They are functional and I don't find them particularly comfortable, nor particularly uncomfortable /shrug.
I am not a tall person, but my upper body is disproportionately long for my height, similar to most 6' 3" or so folks. There's plenty of leg room regardless (I have to scoot the seat up). There's also still plenty of headroom with the top on, and your head isn't sticking up into the fast air with the top off, even given my tall upper body, and scooted forward seat (sort of a worst case I would think).
Despite what I say above about height being well dealt with, I do find my up and forward visibility to be a bit restricted, particularly in looking at stop lights. Often I find myself creeping forward a lot or craning my neck to look over the edge of the windshield, or ducking my head to look under the edge. To correct this, I've considered removing the sun visor on the driver side, since it's tiny anyway and I've yet to use it for its actual purpose. I think that would open up the visibility just enough, and have heard from Tesla that others have done so.
It is tight getting in and out with the top on, but I think that's the case no matter what. If you and your passengers are anything other than rails, you are also going to be well acquainted with the shoulders and arms of your passenger, but that's a width thing, not a height thing
Bottom line, the room is limited, but appropriate for the type of car it is, and they've done a remarkably god job in terms of dealing with height differences.