it plays most like a full-3D Pirates of the Burning Sea, with a constant struggle to balance shields and power distribution while throwing out attacks and evasive maneuvers and all that.
How does it compare to, for example, Eve Online?
It doesn't at all. Travel from system to system involves going to a map type screen and moving around that. I haven't seen any player crafting (doesn't mean it isn't there) and death doesn't seem to have harsh, if any, downsides.
From this video it sounds like they have a WoW-style tank/healer/dps mechanic going. Does that work in the environment?
I haven't seen this much yet, mainly because I haven't seen any "active" abilites, save the one that allows my away team guy to heal one of my other away team guys. This could be the case later, I am not sure.
How much freedom of motion is there in flight? Is it three dimensional? Can I go straight up and attack ships from above?
Yes, although generally it would seem you want to have your side to them because that allows both lasers to fire.
How much of the game looks like fun and how much is grinding for the sake of grinding?
Tough to say. I guess it could be less grindy because combat is more active, on the other hand, it doesn't take a lot of ability to win combat, so if it just becomes "Fly at the enemy, get in range, turn sideways, fire" it will be grindy...
Also the number of loads screens is going to add to the grindyness of it. Some times you literally load into a screen to press the "f" key just so you can get to another load screen. The load times aren't long, but who wants to do that?
How does commerce work? Any crafting systems? Do they make sense?
I honestly have no idea right now. I haven't stumbled across anyone bringing any of this up. One commerce type system in the game is that you can find anomilies and turn them in for rewards. For example, if you find a bunch of biomass and metal ones you can get a shiny new something.
The game is meh. I would agree with anyone who compaired it to Champions. There doesn't seem to be a lot of depth, but it is kind of... coool. It won't give you the stiffy your frist MMO did and it won't have the lasting power of WoW, at least I don't think so.
It also won't have any cool ground breaking features like multiperson ships or boarding parties.
I think it will be fun however, and if a group of my friends decide to play, I will be picking it up.