What is most valuable?
This really depends on the customers requirements. Manageability, transportation and low footprint (and thus higher consolidation ratio) are ones that are often referred to by customers.
How has it helped my organization?
Central management, easy deployment, easy management. This simplifies IT management processes and cuts on project costs and power/data center costs.
What needs improvement?
Licensing cost together with SA.
For how long have I used the solution?
Since ESXi version 3.
What was my experience with deployment of the solution?
What do I think about the stability of the solution?
Depending on guest OS, there are some issues with controller type/driver versions.
What do I think about the scalability of the solution?
None, if you have the resources you can easily scale out (or up)/down depending on your scalability requirements. Autodeploy, host profiles and customizations are a great help here. Further vCOPS will give you valuable capacity management options.
How are customer service and technical support?
Customer Service: Great.Technical Support: Excellent.
Which solution did I use previously and why did I switch?
How was the initial setup?
Straightforward, must have some knowledge though how to implement in the organizations required solution.
What about the implementation team?
I do projects for customers.
What's my experience with pricing, setup cost, and licensing?
Not at liberty to share.
Which other solutions did I evaluate?
Yes, XenServer and Hyper-V are often evaluated by customers.
What other advice do I have?
Don't be intimidated by all the possible functions and comparison reports out there. Look what is needed for your requirements and match to available editions. Also when looking into costs, take the whole into account (not just initial costs, but also consolidation ratios, managebilty and the returns you get from those.)