Rise of Isengard delivers three new slices of Middle-Earth, brings us to Orthanc, and lets us meet Saruman face to face. If that doesn't get you at least a little excited, you're probably not a Lord of the Rings fan in the first place.
If you've played LoTRO before, and all you want is more quests, and new zones to experience then by all means Rise of Isengard is well worth your purchase. But, if you have already burnt out on LoTRO then you won't find anything new here to change your mind.