First we have the Everyone's Song 1 month reminder (yeah, I'm way late). In this drama track, she takes on her role of Bakyura who reminds everyone of the upcoming music competition. Not much else to say about it other than it features a feisty mi~ko who gets upset quite easily over a bumbling Donzumari!
Much more interestingly are the two Musumaker demos. One is a trial version of the game proper and it clocks in at a massive 847MB. The other is a demo of the STG (Shooting Game) mini-game, coming in at a much more palatable 80MB. Both can be obtained from the Musumaker download page.
The STG demo is the most fun of the two and it should be easy to pick up and play regardless of your Japanese skills. Shoot with Z and bomb with X. Hold shoot for beam or tap for spread. While this is no Touhou game, it can get pretty hardcore. Perhaps the most frustrating moment is as the boss approaches: you can easily lose all three of your lives there. Unfortunately the demo does not record scores permanently, but that's understandable.
As for the regular demo, it actually features quite a bit of gameplay. You'll first come across nekomimi-mode mi~ko on February 24, after which her shop opens up. Its inventory is seriously limited in the demo, but it'll give you a good idea of what you can buy. One thing is sure: for a first game, DigitalCute are doing one hell of a job!