I use xscreensaver myself in Linux Mint Maya Xfce, but it was the default for that version (13, LTS). I don't know much about gnome-screensaver. Does that one even have a slideshow? I am not interested in any screensaver without a configurable slideshow. I will say that xscreensaver was difficult to configure in all linux distros. I always forget all the hoops I have to jump through to get it working right, so I have to spend couple hours on research before I can find all the little secrets that are hidden in various places on the Internet. Xscreenaver has been broken for years, so that is probably why LM replaced it with gnome-screensaver. The problem is in GL-slideshow, which to my way of thinking is the only screensaver, the rest being fillers or for people that do not have storage. In GL-slideshow, changing the pic directory requires modifying a file or more than one file. When changing the settings for GL-slideshow, a slider controls amount of time each pic displays. How to set for 1 minute? Guess. Move the slider arrow until it looks like maybe 1/5th of the arbitrary 5 minute maximum. I don't know why there are options like Pan / Fade and other things that distort or move the picture. Next, xscreensaver displays error message on screen due to lack of the "Helvetica" font. That required several hours of research to fix. Finally I discovered that a hidden config file needs to be modified. No, not the same config file, a different one. I think two or three config files? I always forget which one, so I just hunt for them all and change them all. Each one I change so that the "Impact" font is loaded instead of "Helvetica." Not because I like Impact, or because I want Impact, but because Helvetica causes the error message. So xscreensaver today is ... difficult to get working right... but once you get it working, it is OK. I am using it now. Incidentally, JWZ has released several updates (bug fixes) for xscreensaver in 2012, as one can observe by visiting his entertaining and well-designed web site. These updates are not available for *buntu 12.04. Instead, an older version of xscreensaver is in the repositories. I don't know why, but after investing all the time getting xscreensaver working, I decided to leave well enough alone and not bother trying to get a newer version. Hopefully, there will, some day, be a better screensaver available. I don't care about any other screensaver than the Slideshow. The others are curiosities. Maybe they are useful to people who do not have any pictures or who do not have any non-volatile storage in their computer. I plan to leave my systems alone for the time being because xscreensaver is working on both Xubuntu 12.10 and LM Maya Xfce. Don't want to experience the configure xscreensaver ordeal for the time being. Maybe two years from now when the next LTS rolls around.
My desktop runs 64-bit Kubuntu 13.04, my htpc runs 64-bit Linux Mint Nadia Xfce, my answering machine runs 64-bit windows 7, and my laptop runs 64-bit Linux Mint Nadia KDE. Each seems suited to its purpose.