Granted, In Tempest's Wake doesn't add much to the Vanguard story, but it certainly doesn't take anything away from it.
That it is very well written and integrates Vanguard even more into the old continuity and actually opens up the story for a future re-visitation makes it everything but a "disservice".
Perhaps "disservice" is too strong a word. I'm not taking anything away from the story or from Ward, and would probably feel different about it if it would have been labeled as TOS as planned originally.
However, having a VAN story flat out starring Kirk is not how I would have liked the series "last entry" to be. To me, VAN ended the way it should have with Storming Heaven
The ending still stands. Most of In Tempest's Wake
's framing story plays before the framing story of What Judgments Come
and Storming Heaven
. And the last chapter features one of Vanguards main characters with Kirk "only" tagging along because he's needed.
As mentioned before, my gripe isn't with the story but with its labeling and "artificially" extending the VAN series with a post-finale entry...
I still don't like / support the change from the TOS label to VAN (not that I have anything to do about it - it's just my personal opinion)