Long time ago we also assessed GitLab and found it usable but not quite there yet for production use. Though it looks nicer now.
Plus the ability to prevent pull requests from being merged without X approvals, at least one successful Bamboo build etc. It's all very well integrated and polished.
I'm just waiting on rebase instead of merge for pull requests.
I wish it allowed comments in more places than just PRs, but it's been pretty great so far.
I couldn't face Stash after that.
Edit: Atlassian support are excellent but we have to bug them too often with entire sites down (workflow consistency issues fucking the entire JIRA instance which happens at least once a month) for the product to be considered quality.
Reading code through Stash is quite nice as well, much faster then bitbucket.
Gitlab seems to be improving at a crazy pace, which we hope to make the switch to soon.
I'd still like to see cleaner Jira integration.
Edit: Well, sorta. It sounds like Atlassian bought BitBucket but ended up rewriting it as a standalone product (instead of SaaS).
Hey anything is better than SVN which is what we use now!
Give it a try!
On the user side it hits all of the big items and the interface is useable. It doesn't have some features like GitHub's image diff or gh_pages support, but for many things there are Stash plugins that either exists or you can write. And they provide an easy way to not leak internal url's while using gravatar (http://benjamin-meyer.blogspot.com/2014/03/how-to-stop-leaki...)
The biggest downside I have at this point would be that out of the box the permissions model is not as rich/robust as gitolite. Although most Git frontend servers are no where near as rich as gitolite.