Domdaniel: The latter part of the game is a beautifully efficient kill by Taimanov, ripping White apart while wrecking hope of counterplay.
But the opening is fascinating too, not least for its transpositional possibilities (Agincourt is just a generic name for 1.c4 e6 -- French vs English): it begins as a Kangaroo (or Keres) Defence, where 3.d4 would be the mainline, and could lead to a Bogo-Indian, Nimzo-Indian, or Dutch. Instead White's 3.e4 is in the spirit of the Flohr-Mikenas, and Qg4 is common in lines (French Winawer, some Kan Sicilians, etc) where g7 has been weakened. Black's ...c5 is interesting, contesting d4 but preventing the Bishop retreat. And ...Kf8 seems justified.
All the themes are known from more mainstream lines, but combine here in an unusual way. Portisch was/is a 1.c4 English Opening specialist whose style drew comparisons with Botvinnik. Taimanov's play is more like Korchnoi, grabbing pawns in 'heroic defence' mode while simultaneously preparing a counter-attack.
And the conventionally castled White King proves weaker than its walkabout opposite number.
I could just say 'nice game', I suppose. Or paste in some engine spew to sound authoritative.