I loved BeOS back in the day. Such a beautiful and clean interface. I loved the philosophy behind it, and the disdain for 'cruft' as they called it. I still have the discs lying around somewhere...
BeOS's idealism also held it back. They didn't want any ported apps; everything was supposed to be written from scratch. So no Mozilla, no Java, etc. Unfortunately, the BeOS market was never large enough to justify writing large native apps, so they just never happened.
I really hated the small title bars. Never got used (admittedly, never tried that much) to them. We had a BeOS machine at the office in 1998, a beautiful IBM Aptiva S.