If you get a balcony cabin you rarely have an obstructed view. If view is important to you, get the balcony. It is nice to wake up and sit there hearing the waves crash against the bow and listen to the sound of the ship's wake.
Port holes and window, even when unobstructed really present you with a very small view of the outside world. In port it is almost totally useless to have a window because you are so close to the pier and the buildings etc.
IF you know you have an obstructed view try to work with the cruise line to get a better price. These are usually negotiable.
I agree with the post that the cabin is for sleeping and of course for showering. Room service to me is only useful if you have a balcony where you can sit comfortably.
At any rate, have a great time and enjoy your cruise!