Cool idea! I liked that you use the shield mechanic as an incentive to switch up which ship you're focusing on, I would've make that more clear and given it a longer duration though; it's easy to miss that it's happening. Also, I liked the way the ships danced around each other with the inverted controls, but the inverted aiming on the second ship was a real pain - maybe there are other ways to challenge the player to use the second ship, like enemies you have to distract with one ship while you hit them from behind with the other?
Using the link to destroy enemies was also a really fun mechanic!