Vice city heart, at last

I have been peeping into the construction site across the street for weeks, ever since I spotted the small blue Tokyo Metro sticker on a pipe sticking out of its red traffic cones. At last, on Saturday, with flat-screen TVs and white granite walls and Lego yellow floor strips, the Fukutoshin started running.
I took it on Sunday for the first time to get to the train that is normally about a 10-minute walk. It added about 20 minutes to that trip. The second time, we took it home from the middle of the city. The express train whisked us right past our stop, then sat in the tunnel for 15 or 20 minutes apologizing and running an audio (and video) loop about looking out for shady characters and not letting your strollers roll away. By the time we got a local train back to where we meant to be and walked up from the deep track, we had probably spent 40 minutes more than the old trains would have taken.
But it's pretty! They've put murals and mosaics on all the walls, and the seats on the platform
are clear acrylic. There's lots of frosted glass and glowing panels. And a weird pit of trackbed enclosed by concrete at Shinjuku that could be an unfinished track or could be art. It was cool over the weekend that everyone was walking around taking photos with video cameras, long-lens SLRs on tripods and lots of cell phones.
The name of the line means something like secondary heart of the city? The first part of it is usually "vice," as in "vice president." I could look it all up or something, but where would be the fun in that?