Yes it is great fun but the weather can vary. We went in September which was the last cruise of the year with Celebrity - the prices were incredibly cheap. It was a case of sell now or never it seemed.
There are things to do which largely revolve around sightseeing glaciers and wildlife. If you enjoy photography then you will love it.
Shopping was ok. The usual 'gift shops' were plentiful and, for some reason, lots of antique shops. You will pick up cheap salmon and fur whilst there (I scored a gorgeous mink).
There is also a Zip Ride at Icy Straight Point .... check it out
I did and it was fabulous! We went in August. The weather was beautiful. Sunny and not that cold. We went with carnival. I would pick one with a lot of stops. Every site in Alaska was very different and interesting IMO.
We also went on Princess and were very pleased with everything from cabins to food to the onshore excursions and tours. You go through rain forest area along the coast so when we went in June, it rained all week. The week before and after were sunny, so you never know. Bring layers and waterproof jacket if you want to do any rafting or anything near the water. Bring a great camera for all the wildlife.
At the time, balconies were rare and we had cabins with balconies, which I'd highly recommend. The scenery of the glaciers is awesome.