Most ESB products provide HTTP/S adapters out of the box. They are most commonly used as a solution for dynamically and programmatically inserting data into online resources such as forms on web pages. As RESTful web services are not only amenable to the HTTP protocol but in execution pattern almost identical to how web users interact with web forms, HTTP/S adapters are often (in absence of a specialized REST adapter) the best alternative for access to RESTful web services.
The issue with HTTP/S adapters is that they are intended for use with static URLs. Yet RESTful URLs reflect entities being accessed and a URL can be different every time the resource (RESTful entity) is accessed. For that reason, the HTTP/S adapter is appropriate for RESTful services that represent entities such as lists or services where the URL does not change and input to the RESTful service is via configurable parameters.
HTTP/S adapters are also appropriate for RESTful web services that are not written according to the entity pattern (which they often aren't). In that case, an HTTP/S adapter is used to access the static URL of the RESTful web service, and all the information needed by the service is passed on in an HTTP query string. This is the simplest form of a RESTful web service, and the HTTP/S adapter serves this purpose well.
Beyond that, the only further consideration when working with an HTTP/S adapter is selecting the appropriate transformer/mapping component. Most RESTful web services (Hi-REST or Lo-REST) are designed to produce output structured as XML, not plain text or HTML. As XML is the standard format for data representation on ESBs, any ESB used for interaction with RESTful web services should support XML transformation to Java objects or some other convenient data representation format.