I just got the Ultralux buttons recently. And although I am not completely happy with them being a convex button, I think they serve the purpose quite well of having a little eye candy. I use them for the coin buttons and it just gives it a little eye opener, without using them as much of a function button.
That said, they do have a neat housing for the LED's that look better then Groovy Game Gears. A much more manufactured look.
The buttons do feel a little cheaper, and a little nosier, but I am sure they are just as industructable as the rest. They light up great, and thats all I need them for. The bounce are like what you get with cheaper clear plastic.
I really did order them as an extra for a bigger package, but the end result is that I am satified. Just wouldn't use them for hardcore buttons. They definetly lack the precise push of a happs button.
Also mine came with Sanwa microswitches, which again are fine as a nice alternative to cherry. These are first impressions, but I cannot say much bad about them.