What do you like best?
VMware vSphere is the 'big-dog' in the hypervisor market. It's stable, flexible and versatile. vCenter gives you the ability to move your virtual machines between hosts (think 'hardware server') even across the geographical region. It's easy to back up, easy to manage (after just a little training) and with the newer versions, the web GUI is excellent.
What do you dislike?
My biggest issue is the cost--only because we're a state school and it's a healthy portion of our budget.
Recommendations to others considering the product
Do your homework--fully--when you're evaluating virtualization software. Yes there are open-source products (even VMware has a free ESXi) but they're limited in scope and capability. We've evaluated the Hyper-V, but it really doesn't do VDI. We looked at Citrix, but there's not as much expertise in the industry as VMware. We have been approached by Oracle and Redhat to consider their solutions--but support, ease of hiring new employees--is so much better with VMware. Plus if you are in the position--bring existing employees 'up' by getting their certs--and there are few better than the VCD.
What business problems are you solving with the product? What benefits have you realized?
Heat dissipation, power consumption, rack space, management, maintenance, reboot times--shall I go on?