I've purchased from everlane for about a year now. I own a range of things from a wool cocoon coat, trench coat, cashmere, 8 pairs of denim, Day Heels, v heels, boss boot, two silk shirts, and a couple tees (all purchased by me, except the Cocoon Coat which was gifted). I lightly promoted them as an influencer in exchange for $250 worth of product, with no pressure to leave anything but my own opinion.
I've noticed that there are quite a few negative reviews here but in general, I would take them with a grain of salt.
Everlane is a clothing retailer, and one retailer can't make every product flattering to every body type, comfortable for every foot, etc. As with any retailer, figuring out your sizing for the brand is necessary, as not all brands size the same. Example in normal shoes I'm a 9.5, but in Everlane and Italian and French brands I'm a 10.5. Once that is settled, there are far less negative reviews.
My personal experience with everlane has been great. I've returned about 1/3 of my orders over the years, like any other retailer. I use their Happy Returns' option, which is Awesome! My money shows up in my account quickly, and I've never had issues.
The quality ranges from good to great. The pieces I have kept are forever pieces, and the denim is the ONLY rigid denim that fits my body type perfectly and wears really well with constant use. Their shoes have been really lovely quality as well. T shirts, because they are thinner fabric and much cheaper tend to reflect that in quality. I have had to mend one of my t shirts as it did get a hole after about a year but for $18, I'm satisfied with that timeline.
Overall, I really love what everlane is doing for ethical fashion. I found the website user experience and the return process to be really simple, and I am overall pretty satisfied with the pieces I own.