In BitKeeper files work like they do in Unix, there is a (globally) unique name for each file object. Where the object lives in the repository is an attribute of that object, as are the contents, the permissions, who has changed etc.
Here's a super common workflow that's easy in BitKeeper and miserable in Git. I'm debugging an assert. I want to see who added the assert. I pop into the gui that shows me the per file graph and contents, search for the assert, hover over the rev and see that it was done a long time ago. I look in the area above the assert and I see a recent change, hover over that, see the comments and go "hmm, maybe this". Double click that line and I pop into a different gui that shows me the whole commit that contains that suspect line.
Note that because I have a graph per file, I have checkin comments per file. More work for you poor committers but a godsend for us debuggers. More breadcrumbs are more better.
In Git, less breadcrumbs, single commit message. Git wants to go from the rev to the commit, it's miserable to look around in a file and then go backwards to the commit.
When I was supporting BitKeeper our average response time to bug report or a crash report was 25 minute. 24x7. The only reason it was that long was because we were all in North America so there was a window where we were all asleep. Response time 6am-6pm PST was typically under 5 minutes. And I credit the fact that the tool accurately recorded everything and you could find the history really easily.
Oh, and it didn't slow down as the repo got big. Git is fine in little repos but it sucks pretty hard in big ones. Sucks even worse if you are on NFS. I can dig up benchmarks, we built up a synthetic 4M file repo and ran a bunch of tests on it (it was a modified version of the facebook repo builder, the facebook one had some stuff in it that made Git look incredibly bad, we looked at that and decided that wasn't real world or fair, we took that part out).