The faster XenServer dies the better off the virtualization market will be.
It's no surprise that they're tanking - when you have a shitty product people stop using it.
If someone can explain to me why installing an update to Xen Tools requires 5+ reboots of the VM (and even then may leave the VM in an unbootable state requiring a rollback to snapshot) then I might be more forgiving. A service pack to our hypervisor shouldn't require multiple hours of outage for every VM running, and since it DOES we'll just take that outage and use it to migrate to VMWare instead.