I have Panzerschlacht, and it is full of good information. The organization is a bit chaotic, and the text can be hard to follow, but I think it is worth the effort in order to gain a better understanding of these little known battles.
Perry is also a game designer of some repute. 25 years ago, his wargame The Last Panzer Victory was my introduction to the Debrecen battles he covers in his Panzerschlacht book. I got another game of his soon after, Operation Konrad (as revised by the Close Simulations company), and it was my introduction to Konrad 3 and the January 1945 fighting in Hungary. I was 13-14 at the time, and had never heard of these campaigns!