I dunno, I don't mind the installer, its just simplicity wise its so easy for me to just open a zip or rar and grab the files out and put in my folder, i see installers as installing programs, not just packs of models. might cause some minor confusion to some people perhaps.
As for the music i'd probably suggest not to have it, the graphics are nice though. I had my computer muted so i didn't realize there was music going on in it.
Also, one other thing. Personally im ok with rar and everything, but i know windows doesn't have rar support by default only zip. I don't see how people live without rar support these days personally, but i was reminded that some people don't understand them when my dad had a rar sent to him and was completely confused about what to do with it. Probably not as big of a problem among people using models though. I don't know the compression differences between zip and rar offhand, but if its not that big i'd suggest probably using zip, but if it is, just go rar.