I’m well en-route to finishing this quite soon now. I ripped through levels 4 to 7 in double-quick time, although I did miss out on finding one secret level (and I haven’t got all the chests in every level yet either).
I’ve died maybe 5 times now, mostly on bosses. The trick (as always with Kirby) for bosses is having the right power-up when you get to them.
So I’m on Level 8 now, which I thought was going to be the final one (when you look at the map), but things took a detour and opened up somewhere else, so I think there’s at least one more after this. I’m about 70 levels through the 120 too, so it appears that I’m missing something…