It is definitely worth it! There is so much beautiful scenery to see for almost the entire cruise that a balcony is, IMO, very important. We spent a lot of time on ours. You might not lay out in the sun like you would in the Caribbean, but you will use it for sightseeing. Cruising Alaska is different from cruising the Caribbean. We loved Alaska so much we plan to return at least 2 more times. We went on Princess (our first cruise with them) and fell in love with the cruise line, but when we go back, we'll go on HAL at least for 1 cruise, because they have more varied itineraries. We want to see as many new things as possible next time around. I don't think you would go wrong with either HAL or Princess. You'll love Alaska!
Yes to the balcony, especially in Alaska. You just don't want to miss a thing. We did the inside passage round trip from Vancouver and there were some spots that we were very close to land on both sides, very interesting scenery, I loved it. We did find that with the balcony, you could sit out there for long periods of times with the binocs.
We went to Alaska in Aug of 2000 and had a balcony for the first time. It was the greatest for Alaska as you can go inside and get warm and not miss any of the wonderful sites. We saw whales, seal, dolphins by just sitting on the balcony and watching with binoculars.
Balcony is a must!
If depends on when you are going to Alaska. Two years ago we did the first cruise in may on celebrity in a balcony and it was too cold to use most of the time. June-August should be fine on the balcony. We did an outside cabin the next year and enjoyed it fine. HAL has bath tubs in their outside cabins if it is important. You go outside to view the Glaciers anyway.