I'll be honest, I was a bit apprehensive of the best of one format at first. It does however, really ramp up the intensity in each individual engagement. I also like how each team has two "lives" so they're more or less guaranteed to see at least two different opponents in the tourney.
My only concern is teams getting unlucky with map rolls. In my opinion, any teams that draw Duel at Dawn, (in its current, win the first engagement then spawn camp, GG state) for a best of one are quite unlucky. In addition, certain teams are also much more comfortable on select maps than others. Thus, I am not sure it's fair to have say, a sniping team go up against a brawling team on Dunes for a best of one series, (and vice versa for close range maps).
One idea we had to nullify map advantage is to do the map rolls on the fly, with participating teams choosing one map each to take out of the rotation for that match. Of course, this would involve refs having extra work to do pre-match and allow teams to be able to avoid their weakest map, which may not actually be a good thing. It really depends on how much value is placed on (sometimes) forcing teams out of their respective comfort zones.
Overall, a step in the right direction!