plusses and minuses

the plus is that the failover is on vmware so if it does failover none of the SQL services stop. apps just won't be able to connect until it fails over to another node, but all the spid's will still be there. you can also ship the complete VM with all databases to a DR site and just mount it on another VMware node

another plus is that windows clusters are a pain in the *** and changing minor things like IP's can break them. no need for clusters on vmware

upgrading to new hardware is easier. you buy the new hardware and move the VM. no need to reinstall windows

the minus is that the I/O is still limited even if you dedicate drives to each SQL instance. if you have large databases with heavy I/O then you will have problems running them on one vmware node. all the I/O will go through the hypervisor

the db backups might also be a bit slow and you may have to switch to backing up the VM with a vmware aware backup solution like netbackup

the hardware issue can also be a minus. if you have a few SQL instances on a vmware box and you need resources that you don't have you will have to justify a purchase of an expensive server. with non-vmware sql you can buy a cheapo server and move a few databases from various servers to free up resources