Summary:
Excellent chord wood and limbing saw. Always starts and runs all day if you keep it clean. Great saw, but if your a big guy I might recommend the next model up! No parts replaced so far even running 10% ethanol

Strengths:
Very powerful saw for its size. I would recommend running it with a 18" bar to keep the drag reduced. A great saw for somebody who is cutting firewood up to 20" inches in diameter. My advice is let this saw do the work and don't push it when cutting 14" and greater diameters. The saw is very light and manueverable. I have cut between 30-35 chords and so far no problems. Keep the saw clean before every outing to maximize its performance.

Weaknesses:
It can bind if the chain is not allowed enough space to clear the sawdust. Keep the blade out of the snow:) a no brainer. I am 6'4" and would not recommend this saw for a tall person there is a lot of bending over b/c you can't run a longer bar/chain. When felling it lacks acceleration when you get to 18" diameter or greater.

Summary:
Sharp chain and pressing the decompression button on the side is the key to making this saw work well for you. If you've used a 51 in the past you'll like the weight of this but it won't feel as thoug it has as much power. Press the decompression. Find a good chain that isn't a saftey anti kick chain and keep it sharp, and you'll be fine.

Strengths:
Good weight and good power. Runs well. Can take a beating, and keep going.

Weaknesses:
If you forget to press the decompression button on the side the saw becomes a bit moody and may or may not start. When the chain becomes somewhat dull it does bog down.