Here are some of the problems with the Dynamic English repertoire I know of.

1.c4 e5 2.g3 Nf6 3.Bg2 c6 4.d4 cxd4 5.Qxd4 d5 

Kosten recommends 6.cxd5 cxd5 7.Nf3 Nc6 8.Qa4 but after 8...Bc5 Black is fine. White should probably play 6.Nf3 to avoid this line. After 6...dxc4 both 7.Qxc4 and the pawn sacrifice 7.Qxd8+ are good.

1.c4 c5 2.g3 g6 3.Bg2 Bg7 4.Nc3 Nc6 5.a3 e6 

The gambit 6.b4?! (better 6.Rb1) is in crisis: 6...Nxb4 7.axb4 cxb4 8.d4 bxc3 9.e3 Ne7 10.Ne2 d5 11.cxd5 Nxd5 12.Ba3 and now instead of 12...Bf8 (unclear) 12...Bd7 13.O-O Bb5! is good for Black, Domingo - Alekseev, Berlin 2006. 

1.c4 c5 2.g3 g6 3.Bg2 Bg7 4.Nc3 Nc6 5.a3 d6 6.Rb1 a5 7.Nf3 e5 8.O-O Nge7 9.d3 O-O 

Here Kosten's mainline is 10.Bg5 f6 11.Be3 Be6 12.Ne1 Qd7 13.Nc2 a4 14.b3 axb3 15.Rxb3 Andersson - Seirawan, Linares 1983. White won 
a nice game but in later games Black scored very well from this position. I have more trust in 10.Ne1 and 10.Bg5 f6 11.Bd2. 

1.c4 c5 2.g3 g6 3.Bg2 Bg7 4.Nc3 Nc6 5.a3 b6 

Kosten recommends 6.e3 but then after 6...Bxc3! 7.bxc3 Black has the easier game with Bb7, d6, Qd7 and O-O-O and 7.dxc3 is nothing for White.

1.c4 c5 2.g3 Nf6 3.Bg2 d5 4.cxd5 Nxd5 5.Nc3 Nc7 6.Nf3 Nc6 7.O-O e5 8.Ne1 

The line is dubious. The most dangerous moves in my opinion are 8...Bg4 and 8...h5. White should play something else, maybe 6.d3.

1.c4 b6 2.Nc3 Bb7 3.e4 e6 4.Nge2 Nf6 5.d3 

Here Kosten writes that 5...c5 transposes to that chapter's mainline but that's not true. Black gets a very easy game after 6. g3 d5 7.exd5 exd5 8.Bg2 Qd7 9.O-O d4 =+/=. The latest example is Kastek - Rozentalis, Bad Wiessee 2009. 

Hi, I recently got this book and will start working with it. I realize it's a highly regarded book but also a rather outdated book. Can anybody tell me what the biggest theoretical problems in the book are or if there is a resource about this you can point me towards?