Whether an OS is 32bit or 64bit really doesn't tell you anything about the ui. That being said Maemo is just another (relatively) modern llinux distro. In some ways it's a little bit immature and in constant development. When you try to characterize maemo you really have to think about as two parts. The base system is debian-based, but it does have some optimizations to behave better on embedded systems. For example it has well integrated power management and uses busybox instead of coreutils. At the GUI level it's pretty different from desktop linux distros. The gui consists of hildon-desktop, matchbox window manager and apps linked against gtk and libhildon for consistency. There are however many apps using other toolkits. notable examples include liqbase, vgba aand canola. If you have any specific question please feel free to ask.