We're going to Stavanger from Oslo before going to Bergen. Looks like the ferries don't stop in Stavanger and the train takes about 7-8 hours. The fastest way then is by plane. Is the train worth the length of the trip?
Nobody can answer if something is worth for you. Check video clips of this connection on Youtube to find the answer for you.
The fastest way is by overnight train. You go to bed in Oslo in the evening and wake up the next day in Stavanger. But if you have the time to take the day train, it's a very scenic trip.
We did this last summer and we took the bus from Oslo to Kristiansand and then took the train from there to Stavanger. We had a 2 hour stop in Kristiansand, so had lunch there before getting on the train.
Thanks everyone. Of course you can't determine what I consider worth it. We're doing a 6 week trip, and want to make the best of it.