After reading various positive reviews, I decided to give
Sumatra PDF a whirl. (Be careful what "Download" you click on. It's very easy to click the ad if you're not paying attention.)
I tried Foxit PDF a few years back and was mostly happy, until some of the updates came around. Foxit has had some issues with forced ads and has at times fallen behind on security fixes. Last time I looked the interface was cluttered with too much crap. I think part of the problem is that Foxit tries too hard to be like Adobe, but without the bloat. Regardless, Foxit did not work with a work-related program that I was forced to use for a couple years.
Being reluctant to install the full blown Adobe Reader, I used the modified "Lite" versions. Unfortunately, those versions were still rather large (around 80 MB) and the security updates are always several months behind. To help with security, I went into Adobe's preferences and disabled the Java function.
Long story short, I finally decided to try Sumatra PDF (currently at version 1.6). I can honestly say that I am exceptionally pleased with the program. To begin with, it only takes 8.5MB of space on my HDD and it is very fast.
Downloading and installing the program was simple. I set it as default in the program's preferences, and then once for each Internet browser. PDF files now snap to life in comparison to anything else I've tried, and the interface couldn't be easier. The settings are limited, which is ideal for something as simple as reading a PDF file. Besides, I don't need complicated. I just need the stupid PDF to display without a lot of fanfare, flashing ads, and other useless garbage.
For free, the program can't be beat. It's much better than Foxit and infinitely better than Adobe's fat, over-bloated pig. FYI: Sumatra splashes a lot of yellow on the screen during installation, but it displays cleanly when viewing PDF files.