I made a point of driving through there last night and I have to say it does look good in person. I can also confirm that the street-side businesses didn't all disappear as had been originally predicted...
From a motorist's perspective it is no worse than before, as there were always parked cars, street bump-outs for patios, taxis, etc. blocking the side of the road anyhow. If anything it was easier to drive as there were less distractions in the form of people opening car doors or pulling out of parking spaces right in front of you, etc.
I can see where there is no longer any room for a bus to pull over to load/unload that it would be a little slower during busy times, but I'm not sure if that would even be an issue as pedestrians were always the deciding point on how long it would take you to drive through SGR. That, and people driving through to 'people watch'... or 'girl watch' as my friends and I did in our younger days (not sure if that's a thing anymore, or at least not pc enough to be outwardly admitted today?).
Anyhow, it won't matter after June. I'm split on the transit-only thing, TBH. I think overall it will be for the better, but I am curious on how people who arrive by car to pick people up or drop them off will be able to navigate the side streets. We'll see what happens, as is the purpose of a trial.