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And of course he should have recaptured with the queen - but I don't believe that's anything special for black either.
It's not the best opening in the universe, the Hennig-Schara, but because it is so wide open and Black has initiative, it is actually more difficult for White to hold his pawn lead from that position than you might think.
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From several positions after that, Black can force a trade of the light-squared bishop for the knight on f3, creating an isolated pawn and double-pawns which are sufficient compensation for Black's missing pawn (and for losing his bishop).
IQPs can be powerful if you make sure they're not weak; huge space-gainer and tactical threats are possible too. I like the Tarrasch, personally. It appeals to me.
IQPs give you active pieces and squares for those active pieces - in the first IQP tarrasch position with Ne4 all of the pieces have practically been traded except rooks and queens, which is the best theoretical possibility for the side playing against the isolated pawn. In the second one with Nd5, it is white with the active pieces, so in both black is clearly worse. Also, it goes against principle to accept an isolated queen pawn as black, where you don't have development to compensate the loss. I have nothing against IQPs, and frequently get them in certain variations of the QGA, but I don't believe that the Tarrasch is a good opening for black.