For current bugs and to file bugs, please see launchpad:
https://launchpad.net/bzr-search.

Some key caveats though (not bugs per se):

 - memory scaling: Full text indexing currently requires a significant amount
   of memory.  To index the history of 'bzr' requires nearly 200MB of memory
   (revno 3494).  Larger trees are exceedingly likely to require as-much or
   more.
