One morning, I took a Tokaido Shinkansen Nozomi train from Shin Yokohama to Tokyo to try Shinkansen commuting.
Reservation and ticketing are so smooth by EX service by JR Central and JR West. Trains came around every 5 minutes, very frequent.
Regarding the speed of Shinkansen, there will be not so special to add from me (Tokaido is the oldest line (opened in 1964) so maximum speed (285 kmph) is lower than others, and in urban area it is difficult to run at high speed).
Train operation and seat capacity is notable. In winter snowy day, real time delay of 5 or 10 minutes is displayed and announced, (they do too much in this regard, just my personal view). A train set is 16 car and about 1300 seats.
On that day, we sat relaxed even at rush peak period thanks to this and arrived smoothly in Tokyo (19 mins from Shin Yokohama, though we should consider the transfer time or metro and other lines).