What do you like best?
Geopak is a really powerful software package for civil design. In my experience it is more customizable and precise than Civil3d, but that comes at the cost of simplicity. Proper training is really essential, but provided you have some guidance, there is so much you can do with Geopak.
What do you dislike?
User-friendliness is definitely not the strong suit of Geopak. A lot of the nomenclature is not intuitive, and the amount of customization is overwhelming as a new user. It is definitely most useful for someone with a lot of time and patience to dig through the tutorials and training - a luxury I did not always have.
Recommendations to others considering the product
Make sure your clients will accept projects in Geopak. Then, be prepared to dedicate some time to training. It is not something you can pick up just from playing around with.
What business problems are you solving with the product? What benefits have you realized?
I've primarily used it for linear alignment-based projects such as canals and levees. We used the road tools in these cases, but without any real issues. It was generally straightforward to lay out the alignments and profiles. Surface grading was a bit of a challenge and bit laborious. Basically the choice to use Geopak comes down to what the client wants, and what our people have experience in. In my case, TxDOT uses Geopak, and my PM came up in the Transportation group, so we built these projects using Geopak.