Using BeOS was extremely pleasant due to its multitasking prowess, which really had to be experienced to understand how much better it was than other operating systems at the time.<p>Sure, most apps were lightweight and, like allenbrunson said, the pervasive multi-threading model made it harder to develop sophisticated applications, but they must have been on to something because the responsiveness was so good that it felt like you all of a sudden had a computer from the future, where _real_ multitasking was finally solved. It really was something else.<p>The quality of the file system and the way its advanced capabilities were fully utilized throughout the OS was also novel. Here is part of an old article written by Scot Hacker, who also wrote the BeOS Bible, which explain some of the advantages: <a href="http://www.osnews.com/story/421/_I_MacOSX_Week_I_Tales_of_a_BeOS_Refugee/page13/" rel="nofollow">http://www.osnews.com/story/421/_I_MacOSX_Week_I_Tales_of_a_...</a><p>Much of what the BeOS had going for it is now available in other OSes, in various shapes or forms, but what made the BeOS such a joy to use was how it all came together in a unified way. The Tracker, for example, which is the equivalent to Finder on Mac OS X, treated attributes as first-class citizens, making it very natural to set up views like the example in the article above, focusing on Category, Title etc.<p>Another thing that really stood out was the quality of the icons and the look of the window manager. The icons are everywhere on the web today, and while the UI might not be considered sexy by today’s standards, the yellow tabs that could be dragged along the top of windows were cute as hell. Other little touches, like the built-in desktop switcher that allowed different resolutions and color depths for each desktop (excellent for web development), are not commonly found today, afaik.<p>It will be interesting to see what the experience is like now, after so many years with Mac OS X. Will definitely install.