I am a huge fan of it but also know its limitations. Mobile app is a dud IMHO. It seems to have gotten better, but I dont think it can hang with some of the other vendors solutions that are straight html5. But with Ignition, there is always a workaround. I used the webdev module to develop a html website for mobile. If you need graphics then this prob wont work unless you are very skilled with html, but my data is just tabular and charts.
I can sort of say the same thing about it running in java. I run a hosting service, so I have many customers that are accessing the system. Java is always a sore point and I have lost work because of it. The upside is that the java app will run much faster and have more flexibility when doing certain things than a website. At the same time, it is also affected more by slow or laggy internet connections.
I think the notification modules also need some work. Voice notification is limited to 1 channel and hasnt been really optimized to handle lots of callouts simultaneously. Email and sms notification also lacks the ability to retry a user on a roster before moving to the next person on the roster, which I dont understand why since voice allows you to do this. Weird little things like this pop up from time to time which can be frustrating, but overall, especially for the price, I think you cant find a better software.
I really enjoy working in the software. I think if they would eventually move to something that could produce their graphics in an html5 webpage, they would destroy the competition. The flexibility is great. I think sometimes because it is so flexible, that when you cant actually do something in the software it leaves a bad taste in your mouth moreso than it would in another less capable software like wonderware.