When comparing Irfanview vs ImageGlass, the Slant community recommends Irfanview for most people. In the question“What are the best image viewers for Windows?” Irfanview is ranked 1st while ImageGlass is ranked 4th.
Ranked in these QuestionsQuestion Ranking
Pro Some editing tools included (cropping, color correcting, etc...)
Pro Batch processing
Even exif information can be batch processed.
Pro Lots of plugins available
Plugins can be found here.
Pro You can just scroll with your mouse to explore images
Pro Recognizes virtually any image format
Pro Portable version available
If you don't want to or you can't install ImageGlass, you can go with the portable.
Pro It handles animated GIF files really well
Animated GIF files (let it be transparent or regular) are played seamlessly even if you zoom in and out.
Con UI is far from ideal
Sometimes the interface is confusing.
Con GIF viewing is buggy
GIF viewing has longstanding problems like flickering, incorrect framerate or artifacts, and it is very unlikely that it will be ever fixed.
Con Preferences are hard to find
Con No editing options
The program lacks any kind of image manipulation or batch processing features like Irfanview or XnView has. If you're an advanced user, this will be the biggest con against this software.
Con Does not support APNG
It does not support the Animated Portable Network Graphic (APNG) format yet. And it is a con worth considering.