What do you like best?
Ease of use, quick to get started, page linking, online sharing, custom templates, very focused solution. I love that there are not too many distracting features in the UI - it's very clean and intuitive. Another great benefit is the ability to view drafts directly on a mobile device and show them to others.
What do you dislike?
The tool offers a lot of interactions that can be added to elements, but there could be even easier access to all the options. Maybe allow users to create interaction templates similar to the custom templates you can create in the stencil palette.
Recommendations to others considering the product
They offer a full-featured free trial with 31 days time to test all relevant features. You can also invite other users during the trial period to test the collaboration features with you.
What business problems are you solving with the product? What benefits have you realized?
Better communication with clients, quicker turn-around times. I have used Pidoco for a number of projects and found it to be an easy way to share designs with clients and ask them for feedback without the usual email pingpong.