Wow... I'm not sure what you expected or how much research you did with regard to the environmental impact of cruising. As Simon noted above, all of the mainstream cruise lines are firmly committed to environmental protection. Just because you could not see it doesn't mean it isn't happening.
In thinking about this a bit more, I do not go on vacation to worry about where the closest recycle bin is located. I don't mean that to sound sarcastic, but it is a fact. Please take some time to learn more about the cruise line's process of trash collection, sorting, and processing. I know I sleep just fine at night knowing that the efforts made by cruise lines to be as efficient and effective with environmental protection measures. While it may not be perfect (to everyone's expectation), they do a heck of a lot better than many other vacation-related sectors.
As for the remainder of your review, a one star rating isn't justified by the sparse information provided. It is unfortunate that the ship / experience did not measure up for you. Cruising isn't for everyone.