First: its free.
Second: no, its not pay-to-win, either.
Some complain about how difficult it is to get coins for upgrades/ships. I say they need to get better at the game (or shmups in general). My best runs have netted me well over 100k coins. No magnets or revives, only coin-bought power ups.
Also, the starter fighter is actually one of the better ones due to its insanely powerful homing weapon. Later fighters are more interesting, but are sometimes harder to use as well. Ignore the damage stat, as Ive found it quite meaningless so far.
TheGameMaster1234 about Lightning Fighter 2: Space War, v2.0.4