If there's one thing I find annoying to see, it's "the Borg were boring" in TNG. I do not find that at all. They were intriguing upon introduction. They made mince-meat out of the fleet at Wolf359. But then there was this ambiguity about the "stuck in sleep" trick that Data employed. Since Data knew their frequencies, wouldn't he be able to build a transmitter to put a freshly encountered Borg cube to sleep? It wasn't explored, which was disappointing. Then there was Hugh. I thought that was a great episode, exploring the Borg condition. And then in "Descent" we learn of the Borg faction that was created as a result. Unfortunately, that was it for the Borg in TNG. Given how determined the Borg are, I would have expected more confrontations with the Federation. But, they could have become preoccupied with another species or were improving their security protocols for future Federation encounters.
It's true, without a "face" they aren't as interesting. But then, they are also more mysterious. I had some issues with the introduction of the Queen... but if anything, her emotional behavior just seemed so out of place for what the Borg represent.