Doesn't seem like a fair question to me.
SignWarehouse is a huge company with thousands of customers and a ton of products. They do a lot of business. The fact that they do as much business as they do should tell you they must be doing something right. The fact that you can find some posts about a bad experience with them is confirmation that they are operated by humans.
I can say that in the last 12 to 18 months they have made a number of positive changes to reduce the incidences of poorly handled transactions.
My suggestion to you is that if you find them convenient and like what you see, give them a try. The chances are you will have a pleasant experience. If they let you down then shop elsewhere in the future.
I live close to them and buy plenty of Thermal vinyl and
sign vinyl from them. They are convenient for me, when I run out of something.... I also go to Reese Supply in Dallas if need be, or if I buy over a hundred dollars worth of goods, they will ship it to me here in Bells.
Signwharehouse (I call then
Sign Whorehouse) is OK by me. Like anything, they have their ups and downs, but over all, I have learned to deal with any idiosyncrasies that may arise.
The prices are fair enough, and to be able to call, order, and pick up at will call is a big plus for a small operation like ours.
Just be smart, give them the correct item numbers and you should be fine.