I'm just about to finish up the original series. It had its highs and lows, I think the Michael Golden issues cement its status as legendary. There was some stuff in the 30's and 40's that was a chore to get thru.
I bought the New Voyages series about 20 years ago in a 25 cent bin. Don't remember a whole lot about it, but I think it did have ties to the ending of the original, which inspired me to get the original.