Having access to mass transit can be a lifesaver in certain circumstances ... if you know how to use it. Figuring out how to use the subway in a city you've never been in can be a daunting challenge (seriously, look at a map of the Tokyo subway system. It is insane!). With the availability of transit directions in Google Maps, you can let your phone figure out where you're going.
According to Google, "Simply bring up Directions from the main menu and you'll see a second tab labeled Transit (or Public Transport), where you can request a route using only public transportation. You'll receive a number of alternatives that take you (car-free) to your destination. Transit directions are available on Google Maps in more than 50 cities. So whether you live in or are passing through Zurich, Ottawa, Bordeaux, or Chicago -- and plenty of places in between -- you can have Transit schedules in your pocket at all times."
Google also has included a few other features in the latest version of Maps for S60 and WinMo phones. It has added star-ratings for businesses, and it has begun sticking in geographically relevant content and links to mobile map search queries, such as nearby businesses.
Using the software, I was easily able to map a route from 72nd Street and Broadway in Manhattan to Astor Place. I purposely picked a route that I knew would require at least one transfer. The software correctly told me where to transfer to different trains, and if I'd actually had to travel that route, I wouldn't have had any problems (unless the MTA was having a bad day).
Give it a try.