Ahhh, this takes me back. It also reminds me how utterly infuriating the Seeker enemies are. Try to hit them? Missile to the face. Try to hit something else? Missile to the face. Try to land because you're running out of fuel? Nope! Missile to the face. Bloody pain in the arse. I always left them for last when upgrading.
Even all these years later, even in 8-bit form, this game still holds up. In fact, if anything, the authentic Game Boy presentation really complements the game's simplicity. As you said, this really is the exact same game, the exact same experience, just on a Game Boy. When you can distil a game down that much without losing anything, you know you're on to a winner. But we all knew that 13 years ago, right?
Thanks for the trip down memory lane, it's amazing to see all the old creators coming back to give Flash a final send-off.