What do you like best?
High-level advice: always spot on and holistic in perspective.
good ideas on how to execute: planning is definitely a strength, even if actually doing it is an area for growth
What do you dislike?
Staff augment: asking them to do a quick turnaround project that was something of a heavy lift did not always yield positive (or timely) results. You can only ever get two of the following three qualities in a consultant at any given time: cheap, good, fast. H+K might only be good.
Recommendations to others considering the product
Use them for the big think and figure out someone else to do all the little and necessary stuff.