East Coast Brat-
I've got one, and it's perfect for trolling from 0 up to about 2 mph, where my Yamaha 90 finds it's lowest speed, so it's a perfect match.
You need an extra battery or two to troll with it for several hours, and a 40 amp charger and 100 watt or larger generator are great additions to give you unlimited trolling time and distance.
We use it for trolling for trout in freshwater lakes, but it would work for any slow-troll species.
I added it mostly so I could troll very slow, but also as another emergency means of propulsion, but in the ocean or large bays, you'd also need a kicker as a back up capable of dealing with the bigger currents and waves.
Overall, its very good for what it's designed to do, just be sure you don't expect it to have the thrust of a 4-10 hp kicker.
Also, it doesn't work too well in reverse mode, as the thrust from the anti-ventilation plate mounted motor is mostly directed against the back of the transom, neutralizing it.
I'll try to find the thread I wrote when it was installed a few years back.
Here it is!
Hope this gets you started!
Joe. :teeth :thup
Photos of Engine Mounted Trolling Motor Set Up