I wanted to like this plugin, and it has some features not available in other WP plugin:
1- it's not a WP plugin, so it is available in regular HTML sites as well (though Shortpixel is too via a file we install on our server);
2- allows easy image manipulation

But I tested it against Shortpixel's CDN (latest AppSumo deal) and WP Compress (that I recently bought), and here are my conclusions that I put in a post in the Pressdevs' FB group (https://www.facebook.com/groups/PressDevs)...

"I have tested my "classic" choice, Shortpixel (Adaptive Image plugin, using CDN, not the optimisation one that compress them locally) against the newcomers WP Compress and CloudImage (on AppSumo)...

Conclusion? It seems that Shortpixel is still the best, but the others gave me resuts so strange that I'm wondering if everything was okay... Your toughts?

Here's the test site (an Astra template) without any compression (no cache plugin or other): https://d.pr/i/7OzzcO

Here's the same site with Shortpixel: https://d.pr/i/63JQ7b

Now with WP Compress: https://d.pr/i/AiRFSk (the difference is not as big as the score suggest, but still what hurts its score is the Image optimiasation...strange)

Finally, CloudImage: https://d.pr/i/vKzpx7 (I first tested with the JavaScript option enabled, and it was giving some strange blurry images). With it turned off, it's okay, but still compression errors?? And browser caching? They do write that they recommend using a cache plugin when using the JavaScript option, but it was turned off...

Tested all many times with similar results... Guess I'll refund CloudImage, as for WP Compress, it's not written they offer a refund policy...