To @Angi_Hast ,
Following on from your previous reply, I would like to suggest the following improvements to be done for REST v2, otherwise it will never meet value parity to XML-RPC. If anyone else wants to add their own comments, feel free to do so.
SQL Querying Capabilities
The main sticking point of REST, either v1 or v2, is that the Query Parameters are insufficient in a number of areas. XML-RPC has the ability to act similar to a basic SQL request. The link to the documentation is given below. Developers can apply different ways to query the data.
XML-RPC Data Table Query - xml-rpc - Keap Developer Portal
What is need for REST is the ability to run SQL Select statements so that developers can query on particular fields, or even join onto other tables to get the necessary information. I need to point out that some of your larger competitors offer this capability which get around the query limitations of their own endpoints.
Here are some recent examples of developers wanting to do querying items in REST, but are unable to do so due to the querying limitations.
Custom Fields Querying
In XML-RPC we have the ability to query on the Custom Fields, but in REST their is none. Over a year ago Tom Scott mentioned their ware not indexed due to technical reasons. Sorry to say, but that reply is a poor excuse,. How would developers be able to migrate to REST without being able to easily query on Custom Fields? There are integrations out there that will be querying on Custom Fields for a variety of reasons.
Other Endpoints
There has been no indication on when the Ecommerce Endpoints will be fully available as very little is offered so far. Some of the other endpoints, eg; List Subscriptions, are not available. The List Reports Endpoint is confusing when it says its deprecated, so what is the alternative to use?
REST Comments
REST v1 was meant to be the replacement for XML-RPC but feel short in a number of areas. REST v2 is meant to be designed to be the equivalent to XML-RPC, but that is falling short as well. Some of us do need to see significant improvements to be able to migrate across.