I have relied on this program since becoming a Mac user about 3 years ago, and was extremely happy when updates became available after a long spell. However, I've tried to use 3.0.2 and 3.0.3 but wind up reverting back to 2.5.2.1 (which, due to space in the new app's name, still resides on my system, an early-2008 Macbook with 4GB of memory).

The main reason for reverting is the new program's swelling level of memory consumption (currently, with 3.0.3 running and some uptime, close to 825MB), which is excessive. The secondary reasons are things which 2.5.2.1 does very nicely.
* Being able to see the full path name for the current image on the old server status window (rather than just the file name under "Now Showing" in 3.0.3) was very useful. (It was also nice to have the "Dump Cache Information" option in 2.5.2.1 to verify that all images and folders were being picked up.)
* On 2.5.2.1, I always used the "Center" display option to show larger-than-screen images full size but centered on the screen, trimming the edges as necessary. Hence, I'm not fond of the 3.0.3 center option that forces larger-than-screen-resolution pictures to the screen dimensions. The 3.0.3 "Crop" display option comes close to displaying images as I'd prefer, but is inconsistent in what it uses as the anchor point---most often, images are cropped as though they are truly centered (desirable), but I've seen it crop from the upper left, upper right, top center, bottom center, etc.,
* I like having the menu extra to be able to temporarily suspend changes, but it was also useful to use Quicksilver or such to define a keyboard shortcut to open CD as an application, to change preferences, picture sets, and such, rather than mouse up to "Preferences...".

In rating, I have to agree with previous comments that the new interface for choosing folders and sets was not intuitive (and not documented), and that it feels clunky. I would give 2.5.x excellent ratings across the board, but...

I will watch for and try out newer revisions--and again emphasize that I love this program--but, for the moment, will stay with the "old" 2.5.2.1.