We put in a Harman XXV pellet stove in 2008 as supplemental heat. We have a finished basement, and that's where my office is (I work from home), so I wanted something to warm it up. It was always cold in the basement, no matter what we had the thermostat set on upstairs. Much to our surprise, it is more than supplemental heat, and actually does about 80% of the heating of our 1750 sq. ft. rancher (plus fully finished basement) on about a bag of pellets a day. Our heating ill dropped drastically after adding the pellet stove.
We burn about 2 tons of pellets per year. The only issues we have had is a certain brand of pellets (Ozark Hardwood Pellets) are too long (about 3") and clog up the auger, and the igniter is currently out. I haven't replaced the igniter because I don't use it that much. I light the stove with gel, keep it lit, and only shut it down about once every 2-3 weeks to clean the glass. As far as maintenance, above cleaning the glass, I clean the hard deposits off the fire box and scrape the heat exchangers about once a week or so, and give the stove a thorough cleaning twice a year. The thorough cleaning takes about 30 minutes to suck out all of the ash, dump the ash pan, and clean off the combustion fan. That is the only time I need to use a shop vac to clean it out.
I have an inverter and a deep cycle battery (out of our fifth wheel) to use when the power goes out. It only takes about 80 watts or so to run the combustion and distribution blowers, so a battery will last a while. If it dies, I've got a tractor, 2 ATV's, 2 kids' dune buggies, a car each with a battery, and 2 batteries in my diesel truck. Essentially, I can have heat as long as I have fuel to keep one of those vehicles running to charge the battery every now and then.
We had a wood stove when I was growing up, and we thought about putting one in. However, we all have allergies and sinus issues, and a pellet stove is SO much cleaner, and MUCH less work than a wood stove. Plus, it's a much more even heat. We have the thermostat in the basement set on 73. It's 73 in the main part of the basement where the stove is, 72 in the bathroom down the hall, and 73 in my office. It stays about 69-70 upstairs, and our main furnace is set to kick in at 69. Essentially, you get similar heat to a wood stove (though it isn't radiant like a wood stove) with much less hassle, fuss, dirt, dust and work. We love ours, and are trying to decide if we want to put a pellet stove or heated basement floors in our new house we build next year.
If you do get one, make sure you get a good one. Don't buy a cheapie, as you will regret it. I highly recommend Harman. I did a ton of research before buying, and the consensus is to go with Harman or Quadrafire (both are now owned by the same company). We just liked the looks of the Harman XXV over the Quadrafire.