I've got the original series on DVD and am happy with them, but if you can afford the blurays, they're the way to go. On the bluray you can switch between the original 60's FX and updated CG ones.
You'll also want to see the first six movies. Each is quite different, so if you dislike the first (many do), don't stop there. I'm especially curious what you'll think of the second movie, coming to it after Into Darkness