It's pretty good for a while, but eventually gets a bit repetitive. They do stretch for bonkers plot lines sometimes, and some of the dialogue and "science" is a bit dodgey.
Whatever you do, avoid the Miami spin-off like the plague. That is by far the most tragic of the three. The NY one is ok.
Oh and Marg Helgenberger is gorgeous.
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Devious, treacherous, murderous, neanderthal, sub-human of the West.