Watched the original Japanese version with English subtitles.
It's been awhile since I've seen the English dub of the film but besides some minor sub plot stuff this seemed to be spot on. The Willis stuff isn't present but hey Ryo shows up! This is also cannon as it's referenced in season 2.
Plot follow Tai and Izzy as they realize a Digimon has gone wild on the Internet and has pulled a War Games by stealing the codes to a nuke. I haven't seen Summer Wars but I have seen the trailer ten or so times, thanks unskippsble ads! And that film and this ave a very common theme it seems.
I actually enjoy this one more than the first film but it's a different style film altogether. The action is good and I like the character development. Obviously this takes place after season 1 and before season 2.