Honestly I couldn't disagree with you take more. Valhalla was too long and drawn out that it quickly became boring. There was no real payout for gathering allies. For a viking story it seems like someone at Ubisoft said " Let's make an AC game with vikings but make the vikings PG 13"
The combat system for the game isn't that advance. In fact it is fairly simple.
Even for an AC game this is lacking and I highly believe most of the sales it got was from the game riding on the hype of the Vikings Tv show.