Really wholesome. Happy ending - MC female choice is obvious but may incite anger from hardcore fans I suppose. I personally enjoyed the series, so I don't really mind his choice as the ending was really nice.
8/10.
SPOILER: I don't like that the Ex cheated, and yet the MC still went for her in the end, but at the same time, I honestly couldn't see him going out with pet shop lady or the heiress (tsundere, and always too intense), leaving only the former GF. This was the obvious choice as throughout the manga, it was riddled with Erika and the MC memories, still happy ending nonetheless.