Best to follow that old rule of thumb: never book any cabin that is less than you will be happy with. You will usually get exactly what you book.
That being said, that everytime we've ever booked an inside guarantee (6 times), we were upgraded at least one catagory, usually several catagories, and once we were upgraded from inside to oceanview, and that was on a the Golden princess.
Unfortunately after that, we succumbed to the temptation of the verandahs and have booked those ever since. Never saw any hint of an upgrade since then. But I'm not complaining. I now always book exactly the cabin I want. I know this way I am never disappointed.