I've had an insert in my former house (2800 square feet), a wood stove in my current house (2700 square feet), and a wood boiler in my current house. The insert looked really good, but was useless without the built-in fan, since it only stuck out about 7 inches in front of the fireplace bricks. The wood stove worked well with or without the fan (better with the fan), but only heated that one room (80 degrees), with some heat spilling out to adjacent rooms. The wood boiler (in the basement) is hooked up to my forced-hot water radiators, and it heats the entire house at 70 degrees all winter. Since getting the boiler, I don't run the stove much any more (just on really cold nights when the wife needs some extra heat). The boiler is so much more efficient, and I get very even heat throughout the house.
With either the insert or the wood stove, if you aren't positively sure of the clearance and other installation requirements, I recommend you have it professionally installed. It's only a few hundred dollars to get it installed, and you won't have to worry about burning your house down.
After burning wood for 15 years, I would never go back to oil.