They also did that to very great effect in The Hunt For Red October when the camera zoomed in on one of Sean Connery's Russian crew members as he was speaking Russian, then he'd switch to "English" -- letting us know they're still speaking Russian, but now we can understand what they're saying.I would say that previously, the longest Klingon-language scenes were those in TSFS and TUC. Even then, the characters would often just say a few lines in Klingon and then start speaking English mid-conversation, a phenomenon known in linguistics as "code switching."
I like the idea of the Klingons speaking Klingon exclusively -- it adds to their alienness; but I don't think it entirely works. As someone mentioned earlier, your attention is drawn to the subtitles and not fully on the characters themselves most of the time.