U.N. Squadron is a hard-as-a-rock shooter, and it's unique in its personality.
The Bad: Sometimes is hard to break through some stages without leveling up the planes.
U.N. Squadron was one of the first games Capcom brought to SNES, and aside its contemporary Final Fight it was chosen to prove that the SNES could handle good arcade games ports. Daipro originally released it for the arcades in 1989, and it was called Area 88 in Japan.
The game is a side-scrolling shooter that allows you to choose between three different pilots--each one with different abilities--and as you advance in the map completing missions and earning money you'll be able to purchase new planes and equip them with a wide variety of weapons, related to the plane type.
The most important thing in the game's system is how strategy is well balanced with dexterity. You can really make you life easier or harder depending on the way you choose your weapons and plane in the beginning of every mission, it's not just the same thing in different colors. And you must know how to spend your hard-earned money too.
Another great snap about this cartridge is personality: the game is unique not only because of its gameplay, but also because of the game's design--including presentation. For example: when you take damage your plane doesn't crash immediately--your energy bar shows that it's in "danger", and if you manage to avoid being hit in the next few seconds you can survive with a lower energy bar. It's a good way to contour the usually unforgiving gameplay of classic shooters (just for the records it was tested before in Capcom's 1943). Using real planes is also a good sign of personality: developers used to put real planes in flight simulators and spaceships in shooters at the time (again: see 1943). Besides the character design--all drawn in an awesome manga style--with beautifully colored graphics in all the varied environments in the game, and the superb Ultraman-ish soundtrack.
In the end U.N. Squadron is a beautiful shooter for the SNES, and as stated above, it's unique.