Yup, the original concept is the best looking Boxster - simple, compact, clean lines. Took a few pictures of it myself at the Porsche museum last summer.
For my money, the early 986 remains not only the truest to the concept, but also the best looking Box for two main reasons:
1. Clean, uncluttered lines, latter cars get fussier and fussier
2. It looks relatively small and sports car-y. The 987 is only slightly bigger, but looks much, much bigger. The 981 looks almost Merc SL-like in size.
The 986 isn't quite as pretty as the concept, but it's a lot closer that many people seem to think, in my view.
Tell you what, the concept has aged well. Still looks very fresh. Not bad for a 20-year-old effort.