A joke?
No wonder so few downloads.

PROS:

It exists. It's for OS X. It has been updated in the last few years. Lets you set a background image file, page size in pixels or conforms automatically to the dimensions of a chosen background image. You specify number of images in grid, output to PNG, BMP, TIFF, or JPEG, image border width & color, all 4 page borders in pixels, horizontal and vertical gap between images, a filename font, size and color, and a timestamp size, font and color. Yes, it puts the timestamp on the frames. It might do it's thing okay if you're lucky and are willing to fiddle with it.

CONS:

$26 is laughably (a demonic one) overpriced for an excellent app to do this, let alone one this minimal in RealBasic. It's somewhat crash prone if it runs into problems

It provides no options for any information to be included on the sheet other than the filename: No running time, real dimensions, filesize, comment, author, logo, or anything else.

The app displays no progress bar or any other indication of activity except the watch and pinwheel, leaving you wondering if it's hung on a job of any size because it's not all that fast.

If you don't tab or return in a form box, the value doesn't take. There are no dialogs or warnings that I've observed, and no menubar menus. It uses font menus instead of the font panel and non-standard color widgets.

It has just a single method of specifying how the page will be laid out: You provide height and width / numbers of horizontal and vertical frames, and it does what's necessary to jam them within the proscribed borders with the given gaps. It lets the USER do the math (what is a computer good at?) beforehand to determine whether the layout will be practical, and doesn't provide ANY preview of the layout or allow any editing.

There's no positioning other than borders and gaps. Specify 2 x 20 on one of the downloadable backgrounds and you'll get 2 columns of 20 postage stamps down the LEFT SIDE of the page. Won't center them. Ditto for the other direction.

No information is provided about possible input formats, so I assume QT compatible.

Is there one GOOD app for Mac to do this?

I haven't seen one. This is actually less grotty than some. If it were free, I'd probably give it a 4 for value instead of 1.