I thought this was still in Beta (I've been testing but mine finishes at the end of November).
From what I see it does seem to work faster and allow 3-D graphics - you can run Guest Windows 7 machines also with full aero.
Native DVD playing still isn't working and some games might not play properly but I'm not sure I'd pay 99 USD for an upgrade from 6.5.3 unless you REALLY need it.
Buying from NEW I'd take version 7.
I'd still be tempted in your case to wait. - I'm hoping a new (free) version of VMWARE server will be released. I'm using V 2.01 of server and on some machines I have 6.5.3 workstation.
I reverted back to 6.5.3 as I was only using a V7 trial and any virtual machines you create with V7 seem to cause v 6.5.3 to fail with an exception error when you power on the VM. --Not always the first time - but after 2 or 3 re-boots.
(Existing VM's created with 6.5.3 work fine with V7 BTW).