In the main House of M title, the entire core family were at best plot devices. The most developed character in the core eight issues was Pietro who happened to be the surprise antagonist of the story.
In terms of the omnibus, it includes side trades during and after the main series. The only halfway decent family story trades included were of Pietro and Magneto with the Black Panther story and of Pietro, Magneto, and Lorna fighting Doom and his family.
The omnibus is missing three trades it really should not be missing that being Avengers House of M and Civil War House of M. These were the trades that really showed the development of the universe and where the family were more than plot devices.
It also should have included Son of M given the trade decided to deal with fallout of House of M stories. That was better in terms of character development then anything Pietro had in the core title.
What the series still works best for is a very basic introduction to the family to new readers. A lead into stories with much more development. Obviously, it became the starting point story for millions of people done watching WandaVision to find out about the comic version and led into other stories.