The Red Devils landed a 20th top flight crown last season, and their 13th since the introduction of the Premier League.
Remaining at the summit of English football will be no easy task, though, with the likes of Manchester City, Chelsea and Arsenal all looking to knock United off their perch.
A number of the potential contenders have experienced a summer of change - with United having seen Sir Alex Ferguson slip into retirement and succeeded by David Moyes, Jose Mourinho return to Chelsea and Manuel Pellegrini arrive at City.
Giggs says it is shaping up to be another thrilling campaign and admits it has become increasingly difficult to call who will come out on top come May 2014.
He told The Sun: "It is the most unpredictable Premier League ever and it's all very exciting for the fans.
"It's a big change here with Sir Alex Ferguson going - but it's also all change at Chelsea and Manchester City and no-one really knows what is going to happen.
"There are some really good teams and really good managers battling it out, so it's going to be closer than ever.
"All the top teams have great quality. City will want to win the league back, Chelsea have got the experience of Jose Mourinho back and, of course, we are the champions.
"Then you've got clubs such as Arsenal, Tottenham and Liverpool all fighting. It promises to be a really exciting season. But when you are champions you are itching to get back. You want that challenge again and you can't wait for the season to start."