Ubuntu is still half baked. It cannot replace Windows or OS X!
There are plenty of free Linux derivatives around to try. They’re like free candies lying around the web. I’ve tried a few of them (Sabayon, Open SUSE, Mandriva, Fedora and a few more), and among the list, I particularly liked Damn Small Linux. It’s cute and straightforward with only 50MB in size. It doesn’t raise many expectations as a user nor does it explicitly claim/ imply to be a desktop replacement.
Ubuntu is popularly believed to be a complete desktop replacement. And with so many too-good-to-be-true words and promotions about Ubuntu (back in the days) I felt ‘Ubuntu could be my next best and uber-neat OS’. That didn’t work out. Even though my computer’s (Macbook Pro 13 Mid-2010) hardware specifications are more than recommended for Ubuntu; it was still very sluggish – annoying – disappointing. The setting panels and apps took their own time to execute. The default pack of applications still include Firefox browser, which is just another layer to discomfort. And it’s not just my computer – it’s a known problem. With such basic issues on hand (out of hardware incompatibility, driver issues or whatever reason there may be), it’s too soon to claim Ubuntu as a desktop replacement. It isn’t completely reliable yet.
Update – There are mixed experiences regarding the ‘sluggish-ness’ issue. Some users are having no problems, while some are facing severe performance issues even on systems with enough hardware specifications. A google search on this issue will help you undersand more.
Windows and OS X have been under closed development much before Ubuntu was born and with different software development processes. Due to Ubuntu’s open source nature, it is maintained by a large developer’s community and it still has time grow into a complete-reliable operating system. Currently, Ubuntu is NOT a suitable Windows or an OS X replacement.