I have the luxury of in-store Zara shopping. I wasn't sure exactly how much you meant "quality of Zara items" as opposed to "mail-order experience." Re the quality, what people are saying here is true with quality across the board (well, maybe not shabby, but overpriced for some of its stuff). As I said, I can return things in-store so and have never had any issues.
One thing I can say, I ordered my beautiful bag online and it came the next day. Like less than 24 hours later. That's never happened to me elsewhere.