Good for quick photo retouching
My experience has been positive - whenever I need a quick edit, Polarr is usually first in line.
There's a reason why Polarr is known for its filters - it provides a huge selection of ready to use and high quality filters that you can apply with a single click. It also provides good control for image adjustments (light, color, etc).
If you need something a bit more advanced other than filters and photo retouching, then Polarr isn't the right tool for the job.
Excellent for social media images
I have used Polarr to create nicely looking images for social media, especially using its filters.
With a very extensive selection of filters, overlays and tools for basic image editing and retouch, Polarr is very powerful when it comes to editing images for social media.
Its interface is fairly different from most tools out there, so it takes some time to get familiarized with it.