It's not working very well. I was having problems with the stable branch, so I decided to recreated the stable branch from the development one. I just tried to create a checkout of the development repository and I get the error:
bzr checkout /home/antoranz/eclipse/workspace/interfaces stable/
bzr: ERROR: exceptions.UnicodeDecodeError: 'ascii' codec can't decode byte 0xc3 in position 31: ordinal not in range(128)

Traceback (most recent call last):
  File "/usr/lib/python2.5/site-packages/bzrlib/commands.py", line 846, in run_bzr_catch_errors
    return run_bzr(argv)
  File "/usr/lib/python2.5/site-packages/bzrlib/commands.py", line 797, in run_bzr
    ret = run(*run_argv)
  File "/usr/lib/python2.5/site-packages/bzrlib/commands.py", line 499, in run_argv_aliases
    return self.run(**all_cmd_args)
  File "/usr/lib/python2.5/site-packages/bzrlib/builtins.py", line 1024, in run
    accelerator_tree, hardlink)
  File "/usr/lib/python2.5/site-packages/bzrlib/branch.py", line 768, in create_checkout
    hardlink=hardlink)
  File "/usr/lib/python2.5/site-packages/bzrlib/bzrdir.py", line 1260, in create_workingtree
    accelerator_tree=accelerator_tree, hardlink=hardlink)
  File "/usr/lib/python2.5/site-packages/bzrlib/workingtree_4.py", line 1367, in initialize
    wt.unlock()
  File "/usr/lib/python2.5/site-packages/bzrlib/workingtree_4.py", line 1131, in unlock
    self.flush()
  File "/usr/lib/python2.5/site-packages/bzrlib/workingtree_4.py", line 291, in flush
    self.current_dirstate().save()
  File "/usr/lib/python2.5/site-packages/bzrlib/dirstate.py", line 2066, in save
    self._state_file.writelines(self.get_lines())
  File "/usr/lib/python2.5/site-packages/bzrlib/dirstate.py", line 1591, in get_lines
    return self._get_output_lines(lines)
  File "/usr/lib/python2.5/site-packages/bzrlib/dirstate.py", line 1928, in _get_output_lines
    inventory_text = '\0\n\0'.join(lines)
UnicodeDecodeError: 'ascii' codec can't decode byte 0xc3 in position 31: ordinal not in range(128)

bzr 1.5 on python 2.5.2 (linux2)
arguments: ['/usr/bin/bzr', 'checkout', '/home/antoranz/eclipse/workspace/interfaces', 'stable/']
encoding: 'UTF-8', fsenc: 'UTF-8', lang: 'es_CO.UTF-8'
plugins:
  gtk                  /usr/lib/python2.5/site-packages/bzrlib/plugins/gtk [0.93.0]
  launchpad            /usr/lib/python2.5/site-packages/bzrlib/plugins/launchpad [unknown]
*** Bazaar has encountered an internal error.
    Please report a bug at https://bugs.launchpad.net/bzr/+filebug
    including this traceback, and a description of what you
    were doing when the error occurred.

From the log:
0.137  encoding stdout as sys.stdout encoding 'UTF-8'
0.138  bzr arguments: [u'checkout', u'/home/antoranz/eclipse/workspace/interfaces', u'stable/']
0.138  looking for plugins in /home/antoranz/.bazaar/plugins
0.138  looking for plugins in /usr/lib/python2.5/site-packages/bzrlib/plugins
0.138  Plugin name __init__ already loaded
0.138  Plugin name __init__ already loaded
0.160  encoding stdout as sys.stdout encoding 'UTF-8'
0.258  opening working tree '/home/antoranz/eclipse/workspace/interfaces'
0.271  opening working tree '/home/antoranz/eclipse/workspace/interfaces'
0.272  created control directory in file:///home/antoranz/RSN/interfaces/stable/
0.279  creating repository in file:///home/antoranz/RSN/interfaces/stable/.bzr/.
0.283  creating branch <bzrlib.branch.BzrBranchFormat6 object at 0x861108c> in file:///home/antoranz/RSN/interfaces/stable/.bzr/
0.297  Using fetch logic to copy between KnitPackRepository('file:///home/antoranz/eclipse/workspace/interfaces/.bzr/repository/')(<RepositoryFormatKnitPack1>) and KnitPackRepository('file:///home/antoranz/RSN/interfaces/stable/.bzr/repository/')(<RepositoryFormatKnitPack1>)
1.481  trying to create missing lock '/home/antoranz/RSN/interfaces/stable/.bzr/checkout/dirstate'
1.482  opening working tree '/home/antoranz/RSN/interfaces/stable'
1.526  Traceback (most recent call last):
  File "/usr/lib/python2.5/site-packages/bzrlib/commands.py", line 846, in run_bzr_catch_errors
    return run_bzr(argv)
  File "/usr/lib/python2.5/site-packages/bzrlib/commands.py", line 797, in run_bzr
    ret = run(*run_argv)
  File "/usr/lib/python2.5/site-packages/bzrlib/commands.py", line 499, in run_argv_aliases
    return self.run(**all_cmd_args)
  File "/usr/lib/python2.5/site-packages/bzrlib/builtins.py", line 1024, in run
    accelerator_tree, hardlink)
  File "/usr/lib/python2.5/site-packages/bzrlib/branch.py", line 768, in create_checkout
    hardlink=hardlink)
  File "/usr/lib/python2.5/site-packages/bzrlib/bzrdir.py", line 1260, in create_workingtree
    accelerator_tree=accelerator_tree, hardlink=hardlink)
  File "/usr/lib/python2.5/site-packages/bzrlib/workingtree_4.py", line 1367, in initialize
    wt.unlock()
  File "/usr/lib/python2.5/site-packages/bzrlib/workingtree_4.py", line 1131, in unlock
    self.flush()
  File "/usr/lib/python2.5/site-packages/bzrlib/workingtree_4.py", line 291, in flush
    self.current_dirstate().save()
  File "/usr/lib/python2.5/site-packages/bzrlib/dirstate.py", line 2066, in save
    self._state_file.writelines(self.get_lines())
  File "/usr/lib/python2.5/site-packages/bzrlib/dirstate.py", line 1591, in get_lines
    return self._get_output_lines(lines)
  File "/usr/lib/python2.5/site-packages/bzrlib/dirstate.py", line 1928, in _get_output_lines
    inventory_text = '\0\n\0'.join(lines)
UnicodeDecodeError: 'ascii' codec can't decode byte 0xc3 in position 31: ordinal not in range(128)

1.528  return code 4

What do you think? I made a backup of my development branch (just in case) and checked it. It seems to be ok. So I'll keep on working on it.