Well, it's open and lots of folks were already using it to get to their rental cars. First off, it's a rubber tire train (similar to the existing interconcourse people-movers) very utilitarian inside (ie, no seats) and should be very easy to keep the cars shiny and clean. The track is really curvy and the switching is a little rough getting close to the platforms.
Funny rebranding: MARTA is now "City Train" and this is "Sky Train"
It goes Airport --> Gateway Center --> Rental Cars; then the train cars just go backwards back to the airport. Two consists of two joined cars each going back and forth and headways do end up being about 2 minutes.
I'd never seen the Georgia International Convention Center before but the outside looks fine. It's maybe twice as big as the whole Civic Center complex. There will be two hotels at this stop, the Marriott is supposed to open in a couple of weeks and it's hideous. The other one is supposed to open next fall and it looks much better and should relate pretty well to the new train. This stop is kind of funny, each end has a separate elevator/stair tower, so it's kind of like a 60 foot bridge over a dinky little road.
On to the rental facility. The platforms are at the top and then a really interesting tangle of escalators takes you down to the various rental company counters. Really nice piece of work. This is the best concentrated rental facility I've ever seen -- way better than the newish one at DFW. I wonder how many shuttle buses they will be able to get rid of with this move? I hope they've figured out what to do in icy conditions because all of the track bed is exposed. If I ever need to rent a car, I'll definitely be taking MARTA to the airport.
http://en.wikipedia.org/wiki/ATL_Skytrain
Worth a visit. BTW, the architectural model of the new international terminal is in the rotunda and the models of various Sky Train elements are near the MARTA entrance -- nice touch.