I like that we were able to have our own dedicated account manager who was always available for us at any time via email or phone call if needed.
We also liked being given quarterly progress reports with updates about what they worked on in each quarter so there is no question as to whether you should be expecting something from them next quarter. The only thing i disliked (and this could just be because it took me longer than expected) but when doing annual reviews sometimes taking around 3-4 weeks after an event happens before getting feedback back can take some pressure off things! Also having all my emails sent through to one inbox makes life easier rather then using different apps/email addresses etc which made managing lots of communication channels hard to keep up with.