Having been in Madrid and having used the metro, I was also impressed by how well it works. Seemingly always on time, and very good price service ratio. You can buy "rides" and one ride means get in at any station and get out at any other station of the whole network, interchange as many times as you want. For, at the time, 1.16 Euro. Compare that to Berlin, where you can pay some 4 Euro or so for limited amount of stops or time. Madrid metro >> Berlin public transport.
Though in practice if you live there you probably have a Deutschland-Ticket; the 4 euro fee would be primarily for visitors. Even as a visitor you should just buy an X-day pass in the terrible app if you're going to be using it a lot, assuming that the terrible app deigns to let you do that and doesn't just throw cryptic errors.
(What is with German public transport ticket-buying apps? They all seem to be very broken.)