I'm only familiar with a Python clone of the Cassandra implementation ("hydra" -- used it a while back), but two issues I do remember are: 1) I believe it only

I'm only familiar with a Python clone of the Cassandra implementation ("hydra" -- used it a while back), but two issues I do remember are: 1) I believe it only uses 32-bit ints for the bit array addressing, so you can overflow it (and this also may be less-than-ideal from a hash distribution perspective, but I don't know offhand); and 2) as someone coming from a different background, I found the whole thing to have a bit too much "OO" magic, with several helper classes to set up the filter that (to me) obfuscate what's really going on.