Different person but: the Star Wars d20 rules helped me narrow down a couple key problems.
1. If every pc is in their own ship/fighter, it's fine. Everybody gets a whole turn. But if all the pc's are on the same ship, there's only one turn to share amongst the whole party. Usually one pc ends up being the captain, making the main tactical decisions. Other players get to roll attacks or sometimes reactions. It's basically built for quarterbacking. I have yet to see a system that even looks like it would solve this.
2. The system requires feats to be good at piloting fighters or ships - it doesn't let you use standard-blaster-battle class features while in a ship. Even in the case of fightercraft, this means you have to pick at character creation/level up which pillar of play you'll be able to engage in - which is not something I think a game should do. If it's a pillar of play (and space battles are a pillar of Star Wars), every pc should be able to participate. This is relatively simple to solve - even 5e avoids this trap by assuming everyone can ride a horse well and fight from horseback, rather than making you invest feats or whatever to be able to use class features while riding.