What's it like to ride subway trains in Beijng

Is it extremely crowded? I'll need to make trips from the southwestern part of the Beijing to the National Library. I know the lines to take, but is it so crowded that going by subway isn't really a practical option?

If it is off rush hours, it is quite doable, indeed quite a sensible way to get around Beijing. If it is during rush hours, however, train cars are crowded to its limits, filled like satin cans. So, if you can keep flexible hours, like getting out after 9:00-10:00 am or so and won’t return till after 7:00 or so in the evening, you should be all right. With new lines added, the Beijing subway system is pretty good now, connecting all the major destinations in the city. But crowdedness is a fact of life in Beijing, as is traffic jams. In fact, if you have make your trips during the rush hours, taking taxis is not necessarily a better option. Trains are crowded, but they’ll be generally on time. Traveling on surface roads, on the other hand, you may run into predicable situations and get stuck somewhere. But really, avoiding rush hours is the best policy possible. Many visitors from the West are just not accustomed to that kind of crowdedness.

That said, with all the people around you, on trains, in shops, at restaurants, in the streets, there is this sense of excitement, you know, things are happening.