What do you like best?
Great project management, great meeting presence and post-meeting updates, superb implementation, and they managed the budget well.
What do you dislike?
It was a relatively specific feature request that was limited in scope. It feel like it'd be a huge challenge for them if the project was larger in scope and lasted multi-year with a various amount of requested features and functionality.
Recommendations to others considering the product
They'll create a good SOW and project plan well. If they don't know, they'll engage partners who can help. Make sure you are close with their leaders as they can influence their technology leaders and speed things along. Don't be afraid to call meetings with them and request action items.