It's up on our test server for a week and it's in production  (three multimasters) for a day now. I have tested it for the major problems i've seen in the past and it seems to be ok.

The only other semi-cosmetic issue i've found is the statistics of the new dn cache (dnentrycachehits, dnentrycachetries and dnentrycachehitratio in "cn=monitor,cn=userRoot,cn=ldbm database,cn=plugins,cn=config").  The monitor values for this cache do not change at all (this is especially strange for the hits and tries under heavy load) :
dnentrycachehits: 19048
dnentrycachetries: 28571
dnentrycachehitratio: 66
dncurrententrycachesize: 1774672
dnmaxentrycachesize: 10485760
dncurrententrycachecount: 9524
dnmaxentrycachecount: -1

These values do not change at all on high load  production servers for at least 12 hours, from the very beginning...

As for me, this problem is not a showstopper for labelling this version as stable, it can be taken care of in future versions.