I think it's good for the game longterm - what I'm seeing so far is both catchers and hitters being more right than wrong in their challenges....but it's getting to the point where pitches that are millimeters in or off the corner are getting challenged by catchers. So far, hitters seem to be challenging only when there's an obvious ball called a strike.
At some point all the catcher challenges are going to reduce, either by umpires improving or by games where catchers cost their teams challenges for important moments later in games when a bad call winds up not being able to be challenged - it's early yet this season. When we get to a game where a team has lost its challenges and then gets screwed in the 9th on an unchallengeable pitch call, teams are going to recalibrate on when these marginal pitches early in games get repeatedly challenged.
I would say, when a challenge is requested, MLB needs to speed up that process - I don't need to see an ump call for time, announce to the crowd what is happening, and then have a video board take 5 seconds to reveal the call. Just call time right after the challenge and have the video board show the pitch on the screen - make the delay last 5 seconds instead of 15-20.