I think people are being a bit hard on this episode, and perhaps they'll see why in the coming episodes (I hope I'm not wrong by the way about my predictions).
First of all, maybe I'm wrong, but for some reason I don't think this wedding is going to be a 2-parter.
A wedding is a big plot device, because it's a huge event. They're issuing out invites to people so we might see the return of Ohana's mother and possibly Kou (Unless their relationship really is over)?
So it draws together a lot of the cast for this arc, potentially.
Furthermore, the whole plot about the inn, its succession and future, has finally been put on the table by the one who has said the least about it.
The relationship statuses of the characters have finalyl come to a head.
I was very skeptical of Hanasaku Iroha's ability to close up all its loose ends in the remaining episodes, but with this plot device of a wedding, it offers the perfect solution to clear it all up in one swoop.
Now they shouldn't have been in this situation in the first place
... But regardless, I think this is culminating into quite the spectacle, whether or not it turns out well I can't say!
But still it manages to raise the interest levels, by bringing or potentially bringing together so many of the show's big topics to the limelight...
Now if these plot lines or threads don't interest you at all in the first place, then it doesn't matter, but I think there's quite a lot of potential here to do a lot of good for the plot of this show, and I'm pleasantly surprised.
Hopes are up, chance for disappointment and rage are running high...