Canoe trip camping for me is in the eastern US and the typical river bank situation found is well wooded, rocky, and convenient located flat areas for tenting & sleeping on ground are somewhat hard to find at times – and often create clusters of campers.
The Hennessy hammock is very well made, packs small and light (comes with storage bag) and after about 2 "set ups" by a new owner is quick to rig up and get resting. The company internet site is very informative and also You-Tube offers some videos of this product. The hammock is hung between two trees; the main body of the hammock provides a bottom entrance (new models offer option of side zipper) and once in the main body you will find the hammock is shaped not like a normal hammock but is asymmetrical, sort of a trapezoid. You lie at a 15 or so degree angle from the center line, this causes the lower center to cross the small of your back... supporting it. The hammocks solid nylon "bottom" is sewn to a fine screen mesh canopy that is suspended above you. Small items (ipod, keys, wallet, LED flashlight) can be stored/suspended from the ridgeline rope inside this "tent compartment." A separate removable nylon canopy fly offers rain/shade protection. This fly is tied out to side trees, brush or using tent stakes and allows you to vary the amount of side protection... lowered for rain, up for clear screen ventilation/seeing out. You can flip it over and sit in like a chair or lounge in it with out the screening over you.
I swear that this is the most comfortable sleeping you will have outdoors. You can sleep on back, or on your side. No painful hard points on elbows, back, butt, neck. In the heat of summer this is your coolest outdoor sleeping option with full insect protection... PERIOD. I normally use a light fleece sleeping bag and roll my pants into a pillow in temps from 50 to 95+ F. The coolness of hammock sleeping is that air is all around you. At lower temps... you need a closed celltype foam sleeping pad. I normally have a cheep Wal-Mart blue foam pad that is cut about to 2'x3' that I use in canoe for kneeling, on shore for sitting, and in hammock for insulation. I would consider this a three season option... below say 40 degrees you would have to add insulation; there are ways to do this... say a full length Refletex or foam pad and a good down sleeping bag.
How different from tent and things to consider:
Minimal internal storage space; it is just you and some small items in the shelter of hammock, other gear is outside under tarp or hung from trees. There also is not room to easily change clothes, snuggle with your mate, and fido won't fit in here either. Not really an ideal colder climate shelter. You need two strong points to tie to... easy where I go normally, but some areas lack trees or other tie points.
A hammock is great for stealth camping by the way! I often carry this for short day trips also... so quick to set up, so small, so comfortable... zzzzzzzzzzzzz. You never will do that with a tent!