ArcSoft Photo+ is an image viewer that enables you to preview your favorite pictures from your Mac. This program works with a wide variety of image formats, allows you to resize photos with minimum effort, lets you share photos via Facebook or Flickr accounts, and much more.
You can browse folders containing thousands of pictures, display them through a slideshow, crop images to fit a certain pattern, etc. I like that you can also convert photos to other image formats and print them directly from the app's interface.
In my testing, I didn't find any disadvantages of working with this application. However, almost all of its features can also be found within Mac's default image viewer called Preview. Personally, I prefer continue using Preview when it comes to watching pictures.
An advantage of ArcSoft Photo+ is that you can select a picture from a folder and the app automatically loads all photos within the directory. If you ask me, this is the only remarkable difference between ArcSoft Photo+ and Preview.
All in all, if you don't mind spending a small amount of money on a program that lets you preview images in slideshow mode, I'd say you should try ArcSoft Photo+. Otherwise, you can continue using Mac's default app, Preview, for looking at the pictures within your Mac.