A lot of the Canonical-haters, in my experience, speak out of jealousy at Ubuntu's success. They're upset that it's crowded out other distributions to become almost synonymous in popular usage with Linux. Other critics are geeks who feel threatened by Canonical's goal of making Linux accessible to normal people, which they worry will destroy the free-software world by inducting the technically incompetent into it.
It's hard to argue with such critics, as their viewpoints are rooted in opinions and worldviews that can't be easily changed. But there are other criticisms of Ubuntu that are valid and worth considering here.
Not the bestTo start, Ubuntu may not be the most user-friendly Linux distribution. Granted, "user-friendly" is mostly in the eye of the beholder, but there are nonetheless a lot of good reasons for arguing that Mint, for example, does a better job with usability, or that Mandriva makes the system easier to configure through intuitive GUIs.
Nor is Ubuntu the most customizable Linux. Something like Gentoo would win on that account.
A lot of users would argue that Ubuntu, with its earth tones, is far from the prettiest Linux out there.
And while Canonical is responsible for some important projects that benefit the Linux ecosystem as a whole--Launchpad is an example--it can be pretty soundly demonstrated that Canonical's contributions of code back to the upstream projects on which Ubuntu relies is dwarfed by the work of Red Hat and other larger companies.
What mattersSo by some measures and opinions, Ubuntu and Canonical do not represent the best of the free-software world. But despite all this, Ubuntu has succeeded in an important area where every other distribution has failed--specifically, in expanding the image of Linux and free software to unprecedented heights.
Ubuntu has attained a remarkable presence in the non-geek sphere. Mark Shuttleworth has been interviewed by the New York Times and the BBC, a feat of mainstream media coverage obtained not even perhaps by Linus Torvalds himself. Ubuntu's profile in mainstream news sources dwarfs that of its competitors; for a telling example, compare the results of a search of the BBC's site for "ubuntu" vs. those for, say, "fedora" or "red hat".
Canonical has also forged an impressive relationship with vendors like Dell and IBM. Ubuntu isn't the first Linux distribution to come pre-installed on personal computers, and certainly not on servers. But it's the first I've heard of to enjoy advertising in circulars, for example. Dell may not always promote Ubuntu as openly as some would hope, but the relationship has done a lot more than anything prior to bring Linux into the public view.
Canonical's relationship with vendors like Dell has also reaped substantial benefits for the community as a whole. The release of a Linux driver by Broadcom, for example, was achieved through pressure from Dell in order to make sure its hardware would have solid support on Ubuntu.
Ubuntu is not the most technically innovative Linux distribution, nor is Canonical the most prolific contributor of code back to the community. But it has made up for what it lacks in these regards by advancing awareness of alternative operating systems and open-source applications beyond the realm of geeks.
To put it in another light, Ubuntu is to operating systems what Mozilla is for browsers. Firefox may not be the objectively best browser, and Mozilla is hardly the only innovator in its market--more marginal browsers like Opera may best merit that title. But despite these relative shortcomings, Mozilla made the non-geeks of the world realize that the Internet was not the "e" next to their Start menus; it made them (some of them, at least) realize that they have a choice, and that the open-source model can be a viable one.
Canonical's success in bringing Linux mainstream has been only incremental. The Year of the Linux Desktop remains beyond the horizon. But no matter how much we may question certain aspects of Ubuntu, or certain practices of its developers, anyone who hopes to see the Linux desktop go mainstream and the proprietary monopoly broken can't deny the centrality of Canonical in bringing that vision closer to reality in a way that sets Ubuntu far apart from all its competitors.