Interesting:

[Q. Turning to your flight, what is your strongest memory of Apollo XI?

A. Looking back at planet earth from a great distance. (CTF pp470-472; p XVIII) Small, shiny, serene, blue and white, FRAGILE.

Q. That was 40 years ago. Would it look the same today?

A. Yes, from the moon, but appearances can be deceptive. It's certainly not serene, but definitely is fragile, and growing more so. When we flew to the moon, our population was 3 billion; today it has more than doubled and is headed for 8 billion, the experts say. I do not think this growth is sustainable or healthy. The loss of habitat, the trashing of oceans, the accumulation of waste products: this is no way to treat a planet. ]

Anyways, he wasn't at all negative and there's more on that interview here:

From: http://www.nasa.gov/home/hqnews/2009/jul/HQ_09-164_Collins_Statement.html