Citrix NetScaler is suited to any environment where hardware load-balancing, application delivery or SSL offloading is a requirement. It's a product that can be used to manipulate traffic flows in a multitude of different ways and its only limit is the protocol, application and imagination of the administrator. It's not a product that includes helpful wizards to guide the admin through each process gracefully. While it is a fairly intuitive product to use, it's not for someone who is not initiated into the ways of networking and network protocols and communication. Nor is this a product that would lend itself solely for the usage of single usage scenarios where small traffic flows would be expected (although if desired the VPX product would probably suffice in that specific scenario depending on the environment)
The software web application is beyond terrible, in most of the cases the web was broken or did not have similar functionality the command line interface had.
The command line interface wasn't a natural looking interface, it was very fumbled and while it ran on Linux, the interface was all menus and sub-menus.
When enabling different pools for different web services, when a new pool was activated, the old pool connections were all reset instead of allowing HTTP sessions to naturally expire.
I gave the NetScaler a 7 here because the system once configured and deployed is very easy to use. However, if you did not deploy the system and do not have the fundamental background knowledge then you will have trouble using the product in general. Overall it is a great product and service but does typically require professional services to be deployed.
Overall, our organization's experience with Citrix support is that support can be hit or miss. Oftentimes it takes multiple attempts and much longer than desirable to obtain a viable solution for issues experienced with their products. It would be great to see Citrix invest time, effort, and almighty dollars into improving their support and bug fix process across the board.
Netscaler has more features than F5 BIG-IP APM product and easier to manage with friendlier user interface for network admins. It was more cost efficient as well and if you have a Citrix XenApp and XenDesktop environment, it is more compatible with those products as well. Our annual maintenance cost is lower as well.
We moved away from Alteon to F5 BigIP LTM and just by swapping out the hardware, we saw 40% speed increase in our applications. Everything else is much improved as well, from the web interface to the command line to the API.