I just picked this up on friday and wow, did I get engrossed in it.
The combination of tech collection, exploration and different types of play styles really got me into it.
It's sort of like FTL, only with no artificial wall of instant lose behind you. :-D

I played this until the whee hours of the morning one night and most days these past few days and one flaw I realized is that there's WAY too many damage areas that you just can't go around, sometimes 2 or 3 in a row.
The map generation really needs to provide a way around those, instead of forcing the player to go through them one after another.
They could be an alternative of lesser enemies in the roid and black hole places, while going around means more enemies and normal sectors.

I'm not sure weather the ship tree being such a large investment of time to unlock is a good or bad thing.
On the one hand, I feel excited when I get a new ship unlocked; on the other hand it feels like it takes ages to do it.
I can level up my character faster by dying after doing most of the first level, but if I beat all the galaxies I level up only the equivalent of four deaths.
One beat the game takes like 4 hours and gives about 1 level; one first galaxy run takes about 15 minutes and gives 1/4 of a level.
Beating the game needs to give massively more xp.

I agree about the XP and ship unlocking.

The one thing I would change is that you actually gain experience as you play, so ships can be unlocked along the way to gradually improve the fleet.