What version of PHPbb are you on? Have you had any luck? I have no trouble getting it installed and running, but I can't get the importer (exporter?) to complete. Should probably start a new thread, but this one is here, so I thought I'd ask if you were able to get it going.
*I did eventually get the importer to complete. I needed about 6GB of ram to import a 500MB db without out of memory errors. Look and feel is great. Very modern when compared to many PHP solutions. I don't know that it's an acceptable replacement for phpBB at this time if you use a lot of group based permissions. I have 6000 members, and 140k posts over 14k topics. Access to specific forums and features are restricted to certain contribution levels in a tiered structure. I can't as of yet find a way to implement this functionality into nodebb, although I am having a great time playing around with it.