I was recently forced to spend significant time (months!) in the purgative desolation that is MS Windows.

In this hellscape, your options for PDF readers amount to:

"1: No bloat. 2: No spyware/adware. 3: Good UX -- Choose any two."

It made me appreciate just how great Okular is. In my experience, it has a low memory footprint, is snappy and responsive even with large files, and the UX is a dream. Seriously; you wouldn't expect a document viewing utility to look good in and of itself, but Okular does.

But my favorite parts are the little touches you don't even notice, but that just make the whole experience... "luxurious" is the best word I can think of. Some examples of what I love in this regard:

• When you resize the application window, the sidebar resizes proportionally. This doesn't sound too exciting prima facie, but I love using the sidebar's "Thumbnails" tab to navigate, and seeing them dynamically grow and shrink with no perceivable slowdown is really enjoyable.
• Rounded ends on the highlighter tool simulates the look of actual highlighter pens.
• Settings -> Configure -> Performance Tuning makes Okular completely potato-friendly.
• The option to open new files as either separate application windows or tabs in a single window.
• Drag & drop a folder containing images into Okular (or right-click an image folder and say "open with Okular") and you now have an image viewer that lets you scroll through all of the images as though they were a single PDF document.
• Highlight text. Right-click. "Speak Text"
• On the main toolbar's navigation area (where it says, for example, "25 of 100"), click on the number representing the total number of pages. You get a little popup with a scrollbar, allowing you to scroll-select the desired page number instead of having to type it. This isn't decadence, it's accessibility. A really great touch for mobility-restricted users.
• Being able to view PDF, epub, CBR/CBZ comics, and images in one app.

I could probably carry on all day, but you get the idea. I know that some of these features aren't necessarily exclusive to Okular, but they're all present in Okular in an unintrusive, elegant, and bloat-free way.

I don't meant to objectively claim that Okular is the best document viewer out there. I can't make that claim, because I haven't tested that many other document viewers. The reason I haven't done that is because there's nothing Okular hasn't been able to do for me.

P.S. I know now that Okular is available on Windows, but by the time I realized that, I had already moved back to an OS where any perceived enjoyment of the desktop experience isn't contingent on Stockholm Syndrome.