I apologize for the novel this review has become over time with various edits, random updates, numerous additions.
I got two pairs of progressive glasses from GlassesUSA. I was quite apprehensive after reading so many negative reviews here on sitejabber.com. I had previously gotten an awful pair of glasses at a brick-and-mortar chain store for twice the price of one pair at GlassesUSA. My progressive glasses arrived exactly ten days after placing my order, with standard free shipping. The online try-on tool was very helpful and useful. The wide variety of frames, styles, colors, and the ease of sorting through them all by various criteria (including prices, of course) were among the main reasons I ended up giving GlassesUSA a try. The frames I received are decent quality and look fine. I was not thrilled with the lenses as it turns out GlassesUSA does not polish the edges of lenses - which is critical for folks with thick lens prescriptions and/or preferring rimless or semi-rimless frames. With full frames and the recommended super-high-index lenses unpolished lenses turned out not to be too terrible for me. I could not read with either pair at first, which greatly troubled me as I already had a pair of glasses with the same prescription from a brick-and-mortar retailer I could read with just fine. While I waited a week for GlassesUSA to respond - which is absolutely terrible response time effectively killing your time available for return or replacement - I did a lot of research and got some silicone sleeves for the arms of both pairs and some adhesive nose pads for the plastic frames from amazon.com. That greatly improved the issue, which was basically that both pairs of glasses sat too low on my nose, and slid down my nose, and ears, frequently and constantly.
Overall I am pleased with both pairs of glasses. You really have to be ready and willing (and able) to DIY all the adjusting, fitting, and possibly repairing. I saw frustrated customers' reviews who sent glasses back for missing screw(s) and/or nose pad(s) and who wound up without glasses at all when their glasses were not replaced due to their original model having become out-of-stock and GlassesUSA not repairing anything but only providing complete-frame replacements. Apparently the unfortunate customers in question ran out of their precious little allotted time for replacement consisting of a similar item of lesser or equal value - which I also consider deplorable service. As a lifelong wearer of glasses I have a fairly comprehensive glasses repair kit at home, also from amazon.com as well as haphazardly assembled myself over many years, with several different types, sizes, and colors of tiny screws, nose pads, tiny screwdrivers, and other essential glasses repair items - something I'd consider a necessity for folks who wear glasses. I only state this to underscore that you really have to be willing and ready to DIY all the adjusting, fitting, possibly minor fixing, as well as quality control. One of the sets of glasses I received had the nose pads put in backwards, so I agree that quality control, if it even exists, is very poor. So once you actually receive your glasses, you're on your own.
It is nice to not be rushed while trying on glasses that have sat on countless oily noses and ears, and the try-on tool can be lots of fun for trying on lots of styles you might otherwise never contemplate. If you are nearsighted and thus unable to see yourself properly in a mirror with whatever glasses you are trying on, it is a useful tool also.
Update: it is now August 2018 and in all fairness I need to further update my review. I now have had both the pairs of glasses pertaining to this review in excess of 6 months. With extended use, the quality of these glasses proves to be not so great in the long run.
My order consisted of 2 pairs of progressive glasses, one with plastic frames and one with metal frames. The plastic frames are somewhat loose now but continue to be tolerable, the colors are unchanged and overall the frame continues to be attractive, for the most part. The plastic arms of the plastic frames have in some places suffered a very odd patchy superficial wrinkling. It's not too visible when I'm wearing the glasses, my fingertips feel this more than my eyes can see it. The purple metal frames look far worse, but also not too badly visible when I'm wearing the glasses. The ends of the arms (the part that sits on and behind the ears), have a clear plastic sleeve-like covering - as they should. Moisture got into and under these sleeve-coverings and the metal underneath is either rusting, moldy, or both - it is greenish-brown and mottled now and looks rather gross. The clear coating protecting the rest of the arms began peeling and taking the purple color with it, so I had to touch all this up with clear nail polish. None of this has EVER happened to me before with ANY glasses in nearly fifty years of wearing glasses since first grade, so this does not speak very well for the quality of either of the frames. In hindsight I should have painted the arms and sealed off the ends of the arms' plastic sleeve-coverings of the metal frames, before wearing the glasses, with clear nail polish - another instance of DIY. All this strangeness notched my review from 4 stars down to 3 stars.
All in all, albeit only for this one and first order, glassesusa.com has provided acceptable frames and glasses for the low price. Prior to updating this review I went back and read another several months' worth of past reviews. I absolutely concur that the service issues encountered by so many are definitely unacceptable and unforgivable. With this one order I came across some of these issues myself, such as the unacceptably long time to respond to customer complaints or requests for customer service, which effectively greatly reduces the customer's time to file and act on a complaint, giving the company far too much leeway and ability to abscond from their responsibilities. I also found a complaint about something that happened to me also and I neglected to mention: when I filed my initial complaint (that I was unable to read with either pairs of glasses) and asked to return at least one pair, I was also instructed to fill out my complaint form (or whatever online form) on a PC - which I do not have - I have a portable tablet and a smartphone. IF my portable tablet and smartphone are good enough for glassesusa.com to accept an order of several hundred dollars, accept that payment, and process it via a mobile/portable device, they certainly better be willing and able to accept and process everything else on their site via a portable device. This is a ridiculous restriction and demand to place on customers who use portable devices, especially since it can be extremely difficult to access a desktop computer nowadays. I explained exactly this to customer service and they told me to just go ahead and submit via mobile device anyway - this is very possibly another delaying tactic to waste customers' very short and limited time to actually do anything about a problem and render their issue unsolvable. As it happened, I was able to resolve my own issues.
Once again - you get what you pay for. Service and quality suffer ever more the lower the price goes.