I think the GM mode supports the "Spirit of D&D" more than the minutiae of rules. Just being able to adjudicate real time changes to a pre-written adventure based on what a player rolled on the dice is the quintessential requirement, IMO.
I have been playing D&D in one form or another since 1981. I followed the kickstarter, but did not have the money to back it. When the GM mode press release hit, I notified a bunch of my old school crew and one of them bought me the early access as a gift.
We are looking forward to this fall; I have agreed to run a campaign for them. We currently use roll20 to play together, but that is for when they GM. I invested a couple of years in NWN and was very comfortable DMing with that. THIS, looks to be even more in alignment with my GM style.
Kudos to Larian for doing something amazing that blends and enhances the RPG experiences.
