We did one right after we adopted our son, to celebrate my brother-in-law's birthday. We went with Princess, out of Seattle.
I guess I could say - it was ok. Since we had our son, we really weren't able to take full advantage of the Alaskan cruise, since most of the things you're likely to do on an Alaskan cruise - fly over glaciers, go on a whale watch, travel down a zip line etc. aren't exactly "kid-friendly". Or not exactly toddler friendly. One of the truths about cruises is that a great deal of the fun lies in the various excursions. If you're not prepared, you could be bored, unless remaining on board is all you want from a cruise.
I would say, that Alaska is immensely beautiful. Cold - it was late spring, and it was still quite cold. And you can get a quick sense of just how vast and empty the state is - we went to some of Alaska's biggest cities, and they're smaller than Lexington Park. A town like Skagway has ONE old grocery store, and many of these towns have even fewer permanent residents.
We got to see a few whales - briefly. Icebergs all around us - and I didn't know so many of them were pale blue. But given a choice, I think I'd rather do the Caribbean again.