I've been a customer of Merrell for years. I absolutely love their shoes in general (bright colours, good fit for awkward feet, comfortable and durable styles). Prices are the main thing that prevent me from shopping with this retailer more often. While the quality of their outdoor shoes is great, prices are so high compared to other retailers that I am often priced out. I would choose to buy Merrell much more often than I actually purchase but the high prices make this impossible for now.
Price is literally the only part of my experience with Merrell that has been in any way disappointing. I've had multiple pairs of their shoes and have found these to be excellent. I tend to use the Merrell website and have never been to an in-person store. So can't really talk about customer service. Delivery has always been good. I have never used a discount code with Merrell so can't speak from experience about this.
Generally, though, I'm more than happy with my experience with Merrell as far as this goes. One staff off for the take-a-deep-breath prices. Four stars.