We are working on upgrading our old Equallogic SAN for our VMWare enviroment to a new EMC Unity unit. I notice that the new one support virtual volumes where we had the old one configured with datastores. I guess my question in its simplest form is should I worry about switching to vvols during this migration process, or should I stick with the datastore setup I have been using?
If you know nothing about VVols then my advice would be to use datastores during the migration process. A migration is enough of a challenge to get right even without changing the way you think about storage.
Once this is done you can start considering VVols, which offer many advantages. The core one is that you start managing individual VMs rather than storage arrays. And then you get cool things like policy-based management (SPBM, like in VSAN), faster operations (most notably snapshots), more efficient storage utilization etc.
On the other hand, it's a new thing to learn and there are many knobs to be turned, so it's a bit of a curve. Also, it's a relatively new technology and there could be challenges (read: bugs) in implementing it.
The nice thing is that you can run it side-by-side with datastores, so try it out because it offers many advantages. But don't risk your migration over it.