I really like 24 Hour Party People, I also was a bit disappointed about the lack of New Order coverage, but then I realised that, at the effect of the plot, it was the right thing to do... The movie is indeed about three main charachters, the twat, the genius and the poet, there's not much room for someone else, and actually New Order's long and successful career is not appropriate in a story which speaks of Joy Division and their tragic end, and Happy Mondays and their tragic end.
Also, New Order are Joy Division, so the author probably thought they couldn't do a 4 hours movies and it was time to speed forward after Ian's death. Post punk and Madchester are two different periods and Joy Division and Happy Mondays are the perfect stories for those periods, while New Order are less specific.
Of course New Order are still worth a mention, and I don't really think the acoustic version of Blue Monday was a good idea, not at all. I'd have re-created the scene of one of those weird and fantastic early electro performances, like the first versions of Everything's Gone Green (just imagine John Simm hitting his head with the mic after barking and yelling "Jesus I love you!"
) and Temptation, to show the band evolving to a new sound, and then I'd have included a scene with New Order at the height of the acid house excess, like the American tour, but they'd have probably been shadowed by Shaun Ryder's peerless excess...
Still, New Order appear in some form here and there and you do understand their importance, like when you see Bernard trying to produce the Mondays, or the meeting to sell Factory to London Records, the Hacienda history or when they speak in the car about New Order doing a record being important to save the label).
I think they had to make difficult choices, but the film is excellent after all.