POI labels in Maps are auto-hidden when they may overlap with street names. Scroll through the map slowly and you'll see the POI label fade away as a street name appears. Also, smaller/less important POIs like elementary schools can appear briefly and then fade as you scroll, letting you know they are there but getting out of your way until you zoom in more.
These are interesting as it shows a lot of thought going into Maps, though these particular decisions kind of annoy me. Will take some serious getting used to.
Yes, I don't like the way labels and markers often appear and disappear again as you zoom or scroll around. At least in beta 4 they fade in and out smoothly, rather than blinking like in previous betas.