On Grand Princess we were upgraded from inside to obstructed ocean view. The top of the life boat was level with the bottom of our window so we could look straight out with no obstruction. The wheelhouse of the boat (where the driver sits) extended above the top of the boat and blocked the view of the cabin next to ours.
Might as well go for the obstructed view as opposed to the inside if the price is the same. At least you'll have some natural light coming in.
Depending on when your cruise is, you might want to keep checking the Princess site frequently. We did, and I found a nice outside cabin with no obstruction for the same price about 10 days after we booked the obstructed cabin. If we hadn't jumped on it I think we would have been okay. It is better than an inside and there are plenty of things to do with the money you can save. From what I observed most of the ob. view cabins are okay but there are a few that are pretty bad. Even so, you would get sunlight and you'll enjoy of the other great things to do on the ship and at the ports.
I agree with Mike above, take the obstructed ocean view. The thing I don't like about inside cabins is with no llight from the window you never know what time it is. The room is pitch black if you turn the lights out. I will never book an inside again just for that reason.
Always getting a balcony room, we opted for an obstructed ocean view on a Crystal ship several years ago because the price differential was so great we were able to book another cruise on a different line!! The obstruction was very minor, and we were glad we did it!! As mentioned earlier, our obstruction was that of a lifeboat. The good thing was that we were so close to the Promenade deck, all we had to do was wander a few steps and we were UNDER our room on what soon became our private bench!!