I concur; I really like the card-based format of Legion. It harkens back to my early wargaming days with 40k 2nd edition when the battlefield was a covered in cards and tokens. It’s not just a nostalgia thing, either. I think having all the information in front of you is very helpful & much quicker than looking up in a book. It makes it easier to share with opponents too, since they don’t need my army book to look up what the special rules are. The primary draw in the 40k codices has always been the background for me, and Legion has that in the form of movies, books, comics, etc, anyway,