Yeah the new traines are cool, although its kind of eery in this day in age when the train is delayed in a tunnel for any length of time and all you hear are recorded messages. As a NY'er you learn to read the voice of the conductor to sense whether or not the delay is normal or not.
But to answer your question, I do take the 4/5 trains, but even in brooklyn you can end up walking 30 blocks per day just getting to the stop, and then just normal walking around during the day adds up.
Hey I'm not complaining though

I do feel like it keeps you in shape when things get busy.