[I was a co-founder and am a primary developer of Kiln.]
Speaking purely for myself, I don't view Bitbucket as a competitor, to be honest. It's a great tool, but serves a very different purpose.
When it comes to social code, Bitbucket's great. It's Mercurial's equivalent to GitHub, and it fills that role awesomely. I have an account on there where I post stuff I want to be public, including some open-source parts of Kiln's source code, such as our new kbfiles extension.
Kiln, on the other hand, is really focused a lot more on making DVCS a really great experience for companies. A lot of the stuff that makes GitHub and Bitbucket great--the whole social experience--kind of gets in the way of just getting stuff done in a corporate environment. You still want the ability to have personal repos and branches and everything, but you also want really tight integration with bug tracking, really easy ways to follow everything going on with a project in the forms of activity feeds and comprehensive search, APIs to manage everything, a really solid code discussion system so that your developers can talk about code and make sure it's really great before it gets integrated, the ability to quickly answer questions like, "What bugs were open in this point release?" and "Have I contacted customers affected by this to let them know it's fixed?" Kiln and FogBugz together provide those things right now.
I'm sure Bitbucket and Jira could provide that functionality eventually, but it's not what they do right now. And I think that's fine: we need a service that provides really great social tools, and Bitbucket's that. And we need a DVCS hosting solution that's awesome for companies, and Kiln's that. Given that something like 90% of developers still use centralized SCMs, there's piles and piles of room for both of us to coexist peacefully.
Speaking purely for myself, I don't view Bitbucket as a competitor, to be honest. It's a great tool, but serves a very different purpose.
When it comes to social code, Bitbucket's great. It's Mercurial's equivalent to GitHub, and it fills that role awesomely. I have an account on there where I post stuff I want to be public, including some open-source parts of Kiln's source code, such as our new kbfiles extension.
Kiln, on the other hand, is really focused a lot more on making DVCS a really great experience for companies. A lot of the stuff that makes GitHub and Bitbucket great--the whole social experience--kind of gets in the way of just getting stuff done in a corporate environment. You still want the ability to have personal repos and branches and everything, but you also want really tight integration with bug tracking, really easy ways to follow everything going on with a project in the forms of activity feeds and comprehensive search, APIs to manage everything, a really solid code discussion system so that your developers can talk about code and make sure it's really great before it gets integrated, the ability to quickly answer questions like, "What bugs were open in this point release?" and "Have I contacted customers affected by this to let them know it's fixed?" Kiln and FogBugz together provide those things right now.
I'm sure Bitbucket and Jira could provide that functionality eventually, but it's not what they do right now. And I think that's fine: we need a service that provides really great social tools, and Bitbucket's that. And we need a DVCS hosting solution that's awesome for companies, and Kiln's that. Given that something like 90% of developers still use centralized SCMs, there's piles and piles of room for both of us to coexist peacefully.