Fry told BBC Radio Cambridgeshire: "It's been the best ever because Gary Johnson has come in and been very positive from the start.
"We've done our business sooner rather than later which is good."
Welsh international Craig Morgan netted the club £400,000 as he linked up with former manager Darren Ferguson at Preston.
Meanwhile, Posh have made seven summer signings but only defender Kelvin Langmead and midfielder James Wesolowski have commanded fees.
Dave Hibbert, Seth Nana Ofori-Twumasi, Mark Little, and Grant McCann have all arrived as free transfers, while Nathanial Mendez-Laing is on a season-long loan from Wolverhampton Wanderers.
"As usual the chairman has backed the manager and I've been at Peterborough for 15 years and I've never known it such a happy place," Fry said.
Johnson also seems to have been successful in persuading star man George Boyd to see out his contract at London Road.
Fry believes only a manager of Johnson's pedigree could have convinced the former Stevenage man to stay.
"Gary is a proper manager, he knows what he's doing and he's able to get the best out of our players," he added.
Johnson has also confirmed the club are in talks with 26-year-old Aaron Davies, who has travelled with the squad to their training camp in Portugal.
The Posh boss told the Evening Telegraph: "Barry Fry has opened negotiations with the player and his agent.
"He wants to be with us and we want him to join."
The former Nottingham Forest midfielder played under Johnson during their time at Yeovil.
Source: BBC Sport
Source: BBC Sport