Ive driven the 2nd and 3rd generations (i think there are only 3). The first gen are too small for me. The newer ones definitely are nicer but more refined and heavier does take away from the fun driving experience.
My wife has a Miata. I don't care for it. Too small, a pain to climb in and out of and just marginally more carrying capacity than a motorcycle. I can see the attraction to one set up for track use though.