I've had inside cabins on my last three cruises, and I have to say, they really aren't bad at all! they've been designed usually with a mirror that give the illusion of having a window. They are well lit and I tend to go to bed at night and wake up inthe morning. I have a travel alarm clock with a flashlight on the bottom that lights when I lift it.
Most ships have a bridge camera on the TV and you can check the weather and the daylight.
I say give it a try. I never felt claustrophobic or deprived in any way. There are plenty of places to sit and enjoy the ocean. If this is the price point that gets you on the ship, by all means go for it!