Mapzen's services will go away at the end of the month 😢. I'd only used their services in scratching personal itches and the only public project I have using anything of theirs is my trip cast site. Nevertheless, they were a group I enjoyed interacting with and their work over the past few years had pushed the envelope of general expectations for geospatial web services and projects. Their products worked reliably, smoothly, and easily. Their services were easy to interact with, thoroughly documented, and serve as great examples for anyone who wants to build services for the web.
I love the phrase "success hides problems" (credit to Ed Catmull) and can't help but think there's an equally pithy phrase along the lines of "failure masks achievements" that conveys an equally important lesson. Mapzen is closing shop but their legacy will be great work that will live on because so much of it is in the open.
Since their search service will be gone by the end of the month, and since I'm not ready to stop using trip cast, I needed an alternative. I was already using a Mapbox map so I decided see what was involved to drop-in Mapbox's geocoder in place of the Mapzen search service. Turns out, not much! That link goes to the commit with the changes required to use Mapbox instead of Mapzen. Obviously there's a different URL for the service. Other than that, results from Mapbox hang properties for place info directly off of result objects instead of nesting them inside the usual GeoJSON properties object. Not a big deal. The two Mapbox documentation pages that helped me were API docs for response objects and API playground page to search for places. In limited testing, the results are what you'd expect from a place search/geocoding service.