I was lucky enough to find a great deal on a lightly used 12 foot Hornbeck solo/tandem last year. I was hoping I had a boat that would not only be easy to transport but also a great "small stream" boat. My other boat is a 17+ foot fiberglass kayak which is not well suited to small steams as you can imagine. I also thought it would be cool to have a boat I could use as a tandem on occasion even though that wasn't really important to me.
Strengths:
Light weight, easy to carry/portage and easy to load and unload on the car. It is also very comfortable and stable as a solo.
Weaknesses:
Forget using it as a tandem unless you have two smallish passengers that are very similar in weight. It was also very reluctant to turn in small steams due to the hull shape and no rocker. You get a "workout" when you paddle on small streams with frequent turns even when you edge it. Mine was a few years old so, perhaps, they have modified the hull to make it turn easier but the one I had was very hard to turn when you needed to turn sharply.
The final weakness was speed - it's just a slow boat.
While much more expensive, I sold the Hornbeck and bought a Placid Works Rapidfire which I am thrilled with.