Maybe is because I'm from Spain and this is a so-called Euro-Shmup, but men, I usually play all kinds of shmups and I believe there is only two kinds of them: GOOD ones and BAD ones.
Of course, Jet's'Guns belongs to the GOOD ones.
And the weapons are not underpowered like, for example, in Söldner-X (just save money to get the Hexagonal weapon and then we will speak about POWER). Just take a little patience and upgrade the cannons and this game will give you lots of fun.
The only stage I found really difficult was the one that start with a great cubic ship and a voice saying "We are beer..." but I could complete it aftar a few tryings.
I really had a funny week when finishing the game.