I tried yesterday. Worked great, the progress you can make west is amazing compared to the bus.
On pricing. I think it’s still just based on total number of stations traveled. I saw an incredibly complicated fare matrix that even include 5 Yuan for some journeys including the extremity stations, though that might have been in the future.
I don’ think you pay a premium for transferring between lines, we did short trips including line changes and still paid 2 RMB.