Usually there is a lifeboat right outside your window. Often the boat will block most of your view but the windows do let in some light usually. If you look closely at the deck plans, some "obstructed view" cabins are really great. For instance on the Zenith we had the forward most obstucted view cabin and there was only a pole blocking our window. This bar was part of the support structure for the lift that they use to lower the lifeboats. It was a bright and lovely cabin with a great view.
Sometimes you can see between the lifeboats for a little view too. You can tell by the deck plans which cabins have a "peekaboo view."
Use a magnifying glass and study the deck plans carefully before you choose. I hope this helps.