It depends how much you will be in the room. Some people are basically only in the room to sleep, so the upgrade really isn't worth it. You also have to consider the location of the room, which will be better for you. Usually, the ocean views are in a better location.
For me a verandah or ocean view is always a good upgrade. If you are paying the money to cruise, you want to be able to see the water, at least that is how I feel about it. Also consider, if you have no window, it will become difficult to tell what time of the day it is. You may end up sleeping later, etc. Not a problem for most, but can be for others.
Staterooms are pretty small, especially if you have 2 or more people. I think that the window helps to "open" the room up a little. Just a little view outside can help you feel like the room is a little larger, so the room doesn't start to close in.
Really, in the end, it is just your preference. To some the upgrade isn't worth it, to others it is. If you want the view from your room, you can upgrade, if not, don't. Just talk with your friends and majority wins.
It's not a big difference in price, so you just need to consider your options and weigh the pros and cons.
Hope this helps!