What is our primary use case?
We used it to manage a data center hosting environment and had more than 250 HA pairs of Citrix NetScalers (both physical and virtual) to maintain/manage customer environments. Each environment was different, each was a customer-dedicated environment.
How has it helped my organization?
This was a standard load-balancing solution provided to our customers. They didn't have many complaints about the way their traffic was being managed. We were able to handle specific requirements for persistence/stickiness.
What is most valuable?
Content Switching since it provides flexibility for routing traffic as desired to designated real servers. It also provides good geo capabilities through its GSLB feature.
What needs improvement?
Development team's response time could be better.
For how long have I used the solution?
Three to five years.
What do I think about the stability of the solution?
No major issues with stability.
What do I think about the scalability of the solution?
Scalability is good with the virtual appliance, where you can easily scale using the appropriate license and match up with the appropriate virtual machine.
Which solutions did we use previously?
We had a mix of makes/models, as we supported a large customer base, such as F5, Cisco CSS. We have never had a case where we had to switch NetScaler out for another make.
How was the initial setup?
Initial setup is straightforward if you know basic networking concepts. It doesn't take a lot of reading to set one up.
What other advice do I have?
I would rate NetScaler as a seven out of 10 for good technical support on routine issues, but any issues that needed the development team's involvement took a long time.
If you don't have very specific requirements such as the ASM that F5 offers, this would do almost all tasks as far as load-balancing is concerned (geo load-balancing as well).
Disclosure: I am a real user, and this review is based on my own experience and opinions.