Some quick impressions: keep in mind I've only played about an hour. Tutorial (mandatory) and the first mission.
Tutorial does a pretty good job getting you used to the controls. There are only two configs:
I like the gyro controls, but I feel like i need to get used to them. I'm used to dual stick controls when playing shooters, but the nub feels a bit weird and the precision is much better with gyro so far.
Tutorial starts off with aiming, then has you do a shooting gallery test. Next is movement tutorial, and another test in which you defend a stationary ally against a few waves of enemies.
There is some short story exposition as they transition you to the hub, which has you selecting your load out and mission. Story is light at this point: you are stationed at the Bermuda system which has three planets you are watching over. First mission is an extermination mission.
Customization: you can equip "MODs" which are like consumable skills. You can also change your voice (language, gender, pitch), communication phrases (pre-made, but you can select which ones) and paint job (can use Amiibos to unlock. I only got the generic unlock and the Samus ones, but I have a lot of Amiibos. I'll try more later)
Solo play: There is a Lone Wolf MOD you can equip when playing solo that increases your damage input, making it easier for solo play. You can also activate drones that act like Gradius Options which float around you and fire at enemies, which also helps solo play.
Gameplay:
fun so far. Starts with picking your load out (so far I have repair capsules, missiles, super missile and flame shot). Each item has a certain weight. You can only carry as much as your mech will allow. You can get MODs that will increase capacity.
First mission did evoke some Metroid prime feelings of being in an abandoned space station with some enemies around. There is no scanning, but there are stations that you can activate to give you log entries. There are puzzle solving elements involved (getting to some locations to activate switches), and there are some hidden things to find (first mission is on an ice planet, and they recommend you bring the fire shot... I found some hidden areas that gave me MODs. MODs are unspecified when collected.
At the end, you get scored and get medals based on your score. All MODs that were collected are revealed at the end. This loot aspect excites me.
After the mission there was a small debrief and they have some dialogue leading to the next mission.
So far, I like it. I can imagine it being a lot more fun with more people, but the isolated feeling you get with Metroid was present in solo play. I am looking forward to getting more items and MODs.
Any other specific questions, let me know