I love maps. Also, information design in general, like graphs and stuff. But especially maps!
My very first freelance design project was designing a guide/pamphlet around a map for the Ohio & Erie Canal. I met an actual cartographer (Yes! They still exist! MapQuest maps are not magically computer-generated!) and he introduced me to the intricacies of map-making. (Hi, Ken!) Since then I have appreciated maps as unique design problems: like all information design, form must follow function. But form is what the viewer notices first, and bad form can destroy function.redesigned the subway map for the first time in a decade.
Overall the design changes are subtle, but I think they're mostly important. I like the color changes... they feel more contemporary, which feels right for NYC. I think the focus on the bulk of the system makes sense, over the previous map which lent more space to Staten Island. (Perhaps New Yorkers would feel differently... anyone?) The drop-shadow under the subway lines? Eh, not so crazy about that. Supposedly it makes the lines stand out more, but generally speaking I tend to think drop-shadows are over-rated. In this case they were handled just fine, they don't take away from the legibility, but on something with so many intricate details I think adding to the visual clutter was risky.
Take a look at the earlier maps shown in the article as well... I'm a big fan of the simplicity of the 1972 map.