Pros
Working from home, travel, and if you really want, you can surely get away with producing like 0 value, but still get paid.
Cons
Unlike virtually every other technology company in the world, not even top engineers get equity. You better negotiate a high salary, because that's all you get! (and they will pay top of the market - you probably have to lie about your previous salary. do it) And the man who owns it all, makes seriously questionable decisions - often spending a year reinventing technology that already exists, because they can't work with the community. And in the end the new version is worse.. anyway... I don't actually ever see Canonical making it big. Nothing ever works right, at the technology level, and internal turmoil is rampant. Almost the entire rank of VPs were re-hired in 1.5 years. And there are completely dysfunctional teams run by pets of the owner, who are ruining Canonical, but are un-fireable.