For the record, I'm sitting at this instant in Tokyo Station, and am on my way from Narita to Yokohama. I am sitting in the green car, and I accessed the appropriate web page. I have wonderful 802.11 connectivity, and I have an IP address. Whether that means I can use the Internet is another question. On the parts of the track where the connectivity is there, we see ping round trip delays varying from 380 ms to over four seconds. There are fairly large parts of the track where the NTT DoCoMo 3G data connectivity appears to simply not be there - especially when in concrete tubes and ditches, but also on places with open track. So I think here the term "seamless", when applied to connectivity, doesn't really apply.