Unlike the transition from Super Play to N64 magazine, NGC carried on from precisely where N64 magazine left off, with mostly the same staff and even continuing the same numbering system for its issues. The transition started in issue 60, with a new name and new look for the magazine that refreshed the contents, but keeping a similar style - the logo even had the “buttons” from N64 magazine’s logo. In issue 68 the magazine changed its style completely, opting for a more professional, less cluttered look. Printed on extremely large paper, the magazine boasted it was “The Worlds Biggest Gamecube Magazine”, which indeed it was - well for 12 issues at least. Issue 68 also boasted the magazine's first cover disc, which could be played on on both PS2 and Xbox, but couldn’t be read on Gamecube. Doh!!
With the Gamecube gaining more support from third party publisher than the N64, NGC had a wider library of games to cover, and whilst some games may not have got the same coverage as they would have done in N64 - the big games were still given enough space to shine.
With the magazines restyling in issue 68, Planet Game Boy was discontinued. Handheld games were brought into the main reviews area of the magazine, albeit in a shorter format and were given percentage reviews rather than the old PGB 5-star system. This was the case for the majority of the magazines run, however for 2005 and the release of the DS, NGC pocket was launched as a separate section for (you've guessed it) portable games. For the final few issues, and with GameCube games thin on the ground, the DS was incorporated back into the main magazine again.
NGC lasted until June 2006, with the 120th Issue when the transition to the Wii began in earnest. Like N64 and Super Play before it, the magazine had shrunk to a smaller size (A4, Stapled and only 80 content pages) and the quality perhaps had began to wane. Once again, a relaunch was just around the corner.
You can download all the issues of NGC from oldgamemags.com - a fantastic resource for all types of gaming magazines.