I think it's very, very interesting. Clearly it was a flop, basically because Laurents and Sondheim were a little too clever for their own good. It is experimental in the wrong way, partly condescenting towards the audience, critizising and satirizing conformity. I love it.
The plot is rather weird, as is the music, which can be described as very Broadway-y show music used to poke fun at everything. The lyrics are sensational.
I have both recordings. Everyone ought to have Original Cast Recordings of all Sondheim shows, and this OBCR contains sparkling performance by Angela Lansbury. Lee Remick was a favourite actress (and friend) of Sondheim's, so I assume she must have been great. Unfortunately her singing is rather weak, as you also can hear on the Follies concert recording. It's worth hearing, though.
The concert recording of ACW is one of the clumsiest recorded concerts I have heard. It sounds very underrehearsed, is very messy with all the applause, and people often sing wrong lyrics and notes. But when I listen to it, I often get surprised that it is not as bad as I remember it. Madeline Kahn has a very fun voice, but she sounds to be wrong for Cora Hoover Hooper. Bernadette Peters is heart breaking as Fay Apple, but seems to make up her own tune for the title song.
The cut song There's Always a Woman is devilishly clever, a bitchy duel between Cora and Fay. It is recorded for the concert and for the studio recording Unsung Sondheim. The concert version is faster and eviler, but they flub some lyrics.
Basically you should go for the concert recording if you find it, because it is more difficult to come by. The obcr is perhaps a better representation of the show, but it is very cheap so you can always get it later. You won't lose anything by going for the obcr, though, the concert is a worse listening experience.