I have read the so-called "Nunes Memo." As far as I can tell, the report from the House Intelligence Committee says exactly what the previously released Memorandum Opinion and Order from the FISA court itself says. I posted the court document and explanations of it here and here.
The FISA court document, declassified and released, contains confessions from both the FBI and DOJ that the agencies misled the court and falsely acquired surveillance permission. The FBI and DOJ mischaracterize their deception of the court as "mistakes." The agencies provide the court with improvements in their procedures so as not to make "mistakes" in the future.
Why did the FBI and DOJ rush to confess to the FISA court? The reason is that NSA Director Adm. Rodgers discovered their illicit spying, investigated it, and let it be known that he was reporting the FBI and DOJ malfeasance to the FISA court. Adm. Rodgers also informed President Trump.