It's more chaotic than Metal Slug.
There is no speech in Gundemonium Recollection (it IS an Indie game, after all), and the story is told through text at loading screens, but it doesn't matter because story and presentation (which is very good, in fact) are never the reason we play shmups -- it's raw gameplay! This is where the game is awesome. It's more chaotic than Metal Slug. You keep continuously moving and shooting at characters on the screen and face mini-bosses throughout the levels. There are four difficulty levels, which provide many hours of playtime if you play them all. The frame-rate is excellent even when there are a lot of objects on the screen (which there always are). When you kill enemies, countless thingies of different shapes fly out of them, and they move towards your character slightly as if magnetically. The more you get, the higher your score.
Character customization is another one of the fun bits: you can customize the second character, Earl Types, with different weapons and even slightly change her outfit (making her barefoot and disturbing stuff like that). The music is great, and there are two options: arranged, which is the newer one, and the other is the classic music of the arcade game.
On Novice difficulty, your character has to take a shot to the heart to lose a life, however, on Demonic difficulty it is nigh impossible to beat the game.
For its small price, Gundemonium Recollection is completely worth it.