First off, I'd like to say that I am one that preordered. Although it does suck that they decided to cancel the L1, I think it's better then trying to rush an inferior product to market. I'm not saying that L1 would have been inferior, I mean to say that it probably would have been plagued with stability issues, power issues, connection issue, whatever.
A good example would be the Titan. Now I know many people are happy with their Titan purchase, and that they would defend it, but just as many people, if not more, just are fed up with trying to get them running.
From my experience with Bitmain, their products usually have minimal amount of issues in comparison with any other company. Yes the first batch S4's had issues with power, but that's an easy fix really. If bitmain wasn't able to create and support a solid chip with supporting PCB's to power them, then I believe that it was a better idea for them to cancel.
Personally I love it if they would continue R&D as I trust that given another month or 2, they could have created a superior chip. But just imagine if they would have said "We're gonna delays shipment guys, We are now just like everyone else in this business!" Instead they manned up and admitted they can't deliver, and in my opinion, the refund options they have given are fair, as they are offering more then what we paid. Not much for the timeframe of the preorder, but still more.
I believe though that in the future, should they have one, they should stick to their original claims of not being a pre-order company. It has given them a lot of business and why would you want to break the trust of your clients. Trust is everything. Also, I believe they need to be more active with the community. We hardly ever hear from them, Small updates and announcements really go a long way.
This is just my opinions, feel free to contribute in anyway you want, because I know you all will