It starts off really nice. All the visuals and sounds are spot-on. The controls are also very nicely implemented. One thing that bothered me from the start was the low firing rate of the gun; it's something like 2 shots a second.

There are a few powerups you can collect. There's fire and ice, which seem to both just increase damage, there's a missile powerup, which is slower but homes in on enemies and inflicts splash damage, and there's a rapid-fire powerup.

There's also a pickup which will cause Toad to fly in and help you out. I thought this was kind of neat, though Toad dies a little quickly.

I found the fire and ice powerups to be, frankly, completely useless. The missile powerup was useful at first, because there were few enemies, but as the screen became more filled with enemies, the missile powerup became useless. As a result, I had a strong tendency to avoid these three powerups altogether and focus on getting the rapid-fire powerups.

There is also a special powerup that increases the number of bullets you fire at once, up to a maximum of 3 (well, for the rapid-fire gun, at least; I don't know if the max is larger for the others). This is cool, but what irritated me was that collecting the missile powerup drops you back down to 1 bullet. This made me want to avoid the missile powerup even more than I already did.

But really, what I didn't like about this game was that it was too EASY. I only played this once, and I didn't die for nearly 20 minutes! Mind you, this is not how long it took to get a game over, this is how long it took to lose ONE life. I quit the game after that because I was so bored of it. By that time, I had already collected at least 2 extra lives. I felt no pressure at all from the game, and towards the end, I was so bored I just wanted to die already so I could tell how long I survived.