What is our primary use case?
Wireshark can be used to troubleshoot network issues, but also to baseline applications. When you know what an app does when there is no issue at hand, you will be better able to spot the problem when there is an issue. Everything that happens on the network can be analysed with Wireshark. However, the tool is as good as the person using it. You need TCP/IP knowledge to be able to use a tool like this. The more you know about packets on the wire, the better you can use this tool.
How has it helped my organization?
It gives us the ability to pinpoint problems and to communicate network problems with software and hardware vendors. The packets never lie!
What is most valuable?
Making different profiles to tune the tool for the problems at hand, the graphing options, to customize the screen layout, etc.
Also, shines for wireless troubleshooting, but most hardware does not give full insight in WiFi communication (beacon frames, etc.).
What needs improvement?
Big trace files (more than 1,000,000 packets) can be slow, but then you can use "TraceWrangler" (also free) to help with slicing and dicing the data.
This is no complaint, but is not an easy program. You will need to study to use it to its full capabilities (follow a course), but the more you know about it, the more you will use it.
For how long have I used the solution?
More than five years.
What do I think about the stability of the solution?
What do I think about the scalability of the solution?
Big trace files need to be chopped for analysis.
How are customer service and technical support?
My bug reports were in the next release, therefore a great experience.
Which solution did I use previously and why did I switch?
I have used it more or less since 2001. So no, I did not use a previous solution.
How was the initial setup?
Download, run setup, enter;enter;enter..., it is ready.
What about the implementation team?
What's my experience with pricing, setup cost, and licensing?
It is free to download and install. It runs on multiple platforms, so how can you go wrong?
Which other solutions did I evaluate?
In those days, there was a tool "Sniffer", but it was too expensive.
What other advice do I have?
If you profile yourself as a network specialist, and don't use it, I would not trust you on my network.
It is even referenced in the book "TCP/IP Illustrated, Vol. 1", the TCP/IP bible!