Well.... I will have to say I have only taken one cruise and it was a 3 day Disney cruise. It was a blast! The food..... I mean the food.... Did I mention all of the food!!!! It was awesome tasting too. (One of the things I like best about Disneyland is their food in the park is top notch).
Anyway, I went with some of my family and it was a blast, so many Disney characters and shows. It was fun, and it felt nice to feel like I had spoiled myself just once.
As to a regular cruise ship, I haven't felt much of a draw to go on one, probably for the reasons you guys mentioned. The Disney cruise was even more expensive then a regular cruise. I could take a 3 day Carnival cruise out of SoCal for about 1/5th of the cost of the Disney cruise. But I think most people know that going in. I wouldn't do it everyday, but as a once in a lifetime type thing with some of my family, it was great.