I've used slideshow_ck on my passion-usa.net website for large (100-200) slideshows. This extension is very easy to use, yet allows great customization. I would definitely recommend using the plugin (it carries a small fee) in connection with the extension. it makes things easier, with a richer feature set at the same time. I like them both and intend to use them for a long time.
I still have an outstanding support issue, but it may be caused by IE9 being a non-standard browser more than this extension. Anyway, it's currently under investigation, and it won't decrease my rating.
All in all, the rookie in me loves it. Great job, Cedric !