Barely more, and fine, but not nearly the priority a lot of other things could be. This is the same marginal upgrade you're arguing against in the 5th starter thread.
Hamilton plays every day and will play in the playoffs. A 5th starter will not
Hamilton is better offensively, simply due to more steals and not striking out as much. Combine that with Hamilton's performance last season, where he posted a .320 OBP, and Hamilton is a decent improvement over Michael Taylor, offensively. Ideally I'd like Lorenzo Cain or Kevin Pillar, but that would probably involve giving up Robles or Fedde. Hamilton is MUCH better defensively than Taylor, which will be an every day thing in the playoffs (there are still people nagging about Turner "costing" the Nationals game(s) in the playoffs because of his inexperience in CF).
This also gives you an outfield for next season, when Werth leaves.