I think TestStand is great. However, if I had a suggestion, I would say to provide more varities of Operator interfaces. It is cool that you have a simple and full featured operator interface. But you could help your customer's out more if you provided operator interfaces in .net and labview that fit a more variety of circumstances. For instance, the current simple and full featured operator interface is not ideal for batch process models where multiple duts are being tested at once. The simple and full featured operator interface justs shows one dut at a time to the operator. It would be nice to see the steps and events of all duts at the same time. This would especially be useful in a manufacturing environment. Currently, I am customizing my operator interface based off of NI's full featured operator interface in c#. I customized it to show all dut sequences at the same time so the operator can see all that is happening on the GUI. That is just one example. I am guessing NI thinks the simple and full featured operator interfaces is good enough and that it allows your customer's to customize them anyway they want. That is true. But if there were more varities available, it would help reduce your customer's developement time and win more favor than you already have with TestStand. Also on another note. I also had to customize the UUT Dailog Box to fit my needs for my application. If you could make it easier to customize UUT dialog boxes that would be cool too.
please do not revive a 5 year old thread asking for performance feedback with a post for feature requests.
However, you can find some feature suggestions in the TestStand Idea Exchange forum like this.
Also, there are examples for UIs available in the NI community like here.