The analogue control system in this game is dreadful. You can move at only two speeds. A slow crawl, or full throttle. The slower speed requires you to barely touch the stick on your controller, but applying even the tiniest bit of extra pressure causes the plane to abruptly jump to top speed.

This makes precise control difficult, and that's BEFORE you purchase any speed upgrades. These upgrades are now effectively permanent downgrades which make the game a lot harder. If you try to move quickly, you plow into waves of enemy shots or planes and die very quickly, or at least take heavy damage. If you try to move slowly, you will inevitably apply slightly too much pressure to the control stick from time to time, causing you to suddenly jerk in the direction you are moving and likely crashing into something.

The control system is currently unmanageable, and I would urge the developers to correct the problem as soon as possible. Analogue control should be precise and intuitive, and this system has failed on both counts.