Groove Machine is darker and much more serious looking. FL mobile looked a little more like the Walkband than FL. In many ways it feels like working in FL rather than FL Mobile with the piano-roll and the darker colour scheme. I was never a serious FL fan on the PC but I think those that are will get a lot out of the Groove Machine. You get some ideas using one app trying to do something and then you realize how much easier it is to do it in Caustic so your technique is evolving. Groove Machine on the other hand, well, as I said before, it's cluttered, but if anything it's an educational experience. Some apps I buy I try to hang onto for as long as I can get use out of but in the case of FL mobile I don't think I'll ever go back to trying to use it. I suppose it's a welcome addition to the array of other music software I now use. I broke down the other day and bought it and I'll let you guys know what I think about it.