I used them, and am currently using them
So far, no complaints! They send you a box and its really easy and convenient to ship
For me I sold my iPhone 4S 64GB for probably about 18$ less (only 18$!) than what the going price was on my local kijiji ads.
To me, that was worth it especially to not have the hassle of kijiji low ballers and no shows and waiting for your phone to sell and all that headache. I'll gladly forfeit 18$ for that. Also much better than trading it it elsewhere (about 200$ more than what best buy was offering for example! Almost 130$ more than trading it in to apple store too) or selling it on ebay and having ebay fees take a large chunk of the sale price
Orchard is a good option if you have a fully functional and working iphone, and you just want to get rid of it for a fair price without any hassle. The only thing is, if you want the max value for the phone you have to wait 3 weeks (from the time they receive and inspect the phone).
Just download the app, be truthful, and its very convenient overall. Wish they had something similar for iPads