I still enjoyed it mostly up to the end, i feel it just lasted so long on the strength of the earlier seasons and got sillier and sillier. Ted is a brilliant character though and worth watching for varying Ted'isms.
I can see the correlation but no, I wouldn't class it as such, a costume drama to me conjures images of stiff upper lip british romance, this is the polar opposite of that.
I'm personally glad a few shows that I enjoy, such as The Boys and The Expanse went for the weekly release route. Gave me time to dwell on each episode and give it some thought and have something to look forward to the next week. On the flipside, it exposed how bad the writing on S2 of The Boys actually was