Quoted from jar155:KISS just isn't much fun. Unless it's a total code overhaul, the game isn't going to magically become fun with a few more added features and tweaks. I don't think that the layout is a dog, but it's pretty plain. It's not challenging enough to get away with being plain (like Iron Man), and the code isn't fun enough either (like AFM). I think KISS just fell into a bad spot with its initial code release and building on what was pretty lame hasn't worked. I don't think it can work unless they try again with a better starting point. It's not impossible, but an incremental upgrade won't do it.
I think it's fun, and I don't think there's anything wrong with the layout. Completing songs and completing the grid seem to be the majority of the game right now, but I see potential for a lot more with code updates. I disagree with it not being challenging. If you are attempting to complete songs to reach 2x, 3x, 5x, and Colossal (10x), that is extremely challenging. The left orbit between the pops is challenging, at least on my game. I've owned many other games with the pops surrounding the left orbit, and this shot on KISS seems to be the most difficult for me. I had no problems with XM, TSPP, SWDE, JP and a few others, but maybe because those were all a little closer?
Another thing that has helped make this game more fun for me is the song changes I've made. I added "God of Thunder" for Demon MB and moved Dr. Love to the song list. I added "New York Groove" in place of "Heaven's on Fire," and I replaced a few songs in the song list with "Strutter" and "I Was Made for Loving You."