I transferred from T2 to T3 yesterday. It was shockingly long and unpleasant.

1. It's hard to believe in this day and age, an airport of a modern city like Tokyo has no train connecting passengers between terminals.
2. We waited 20 minutes for a bus to arrive. That's unacceptably long, and it wasn't even able to accommodate all queued passengers. I hope they didn't have to wait another 20 minutes.
3. The drive took at least 15 minutes. I was starting to wonder if we were being hijacked.
4. Passengers were packed like sardines.

I once had an I-I transfer in Tokyo with a 45min layover. With this terminal transfer, if I had anything under 1.5 hours, I would have had zero lounge time and in danger of missing the flight.

In contrast, I landed in KUL a few hours later (on ANA). Their aerotrain being out of service, they had business class buses ferrying J pax from Satellite terminal to Main terminal. The bus seats were opulent and spacious, there was no wait, and there was even a mini waiting area with tea. It put ANA's HND transfer experience to absolute shame.