Have used it for some hours today and it is highly recommendable with some reservations.
It is a I think a must buy for anyone that likes to use samples in their music.
I will write a review of Yellofier in the days to come.
One thing that has to be said now though is that the recommended specifications are too low. They have put it at Android 2.3.3 and it would surprise me if it worked okay on more than maybe a couple of phones.
Will try on my HTC wildfire but have tried it on a Vodafone Tablet with Android 3.2 and it worked more or less in the beginning but it was struggling and now it only opens up unto a frozen page when starting the application.
So remember that if your device is not strong and even if it is said that it is supposed to work be ready to use the fifteen minutes to test the application before hand...
Think that you should not have to high expectations unless you have a device with 4.0 or over.
Until then here is some promotional videos and a album that was posted (as was some of the videos) before but posting it again as it was made using only Yellofier.