There's a lot of celluloid that I *don't* like -- I absolutely hate all the pseudo-pearl/cracked-ice/whatever celluloids - quite accurately called MOTS in my opinion (Mother Of Toilet Seat); so called christmas tree cel is another high on my list of loathing (as indeed are all other horrible patterns that look like a carnival ate too much glitter and got really sick) -- but I also hate all the acrylics similar to these - my loathing is for the patterns and the nasty garish colors, not the material used. It's just that cel allows for some especially horrible excesses in creating such abominations.
But the same flexibility can allow for creating remarkable patterns, with subtle 3D figuring, translucence, and chatoyance that no other material can do -- like the finely lined and patterned French ivory and waterfall celluloids and the tortoise shell celluloids. There are other colors, patterns, and textures that they were able to do in cel that no other material has gotten close to -- crushed velvet being one of them (I have a Winchester in a deep red and black crushed velvet cel that is remarkable). Even the beautiful and relatively simple candy cane cel has not been properly captured in any other material. It's the 3D quality with very precise control of transparency/translucence/opacity (all within the same pattern) plus the ability take very fine - even geometric - details that good cel can bring that really sets it apart.