Pros: Took green and dry branches up to about 2" in dia. Machine easy to move.
Cons: Somewhat light gauge metal might not survive abusive owners over long run.
I purchased a used 8.5hp Sears chipper to make mulch from shrub and tree prunings on my 1 acre lot. I believe Sears has discontinued this model. However, in the $300-400 range used, it is a decent value (I paid $375 in June 2004 for a used one in nearly new condition...included bag, owners manual, original receipts and a few small extras).
The seller had already changed the spark plug, air filter, and oil. All of those items are easily accessible. The oil drain plug has a nice long extension that puts the drain out where you'll be able to catch the oil. That left me to check/sharpen the chipper blades and shredder blade.
There are 2 small chipper blades that are attached by flush bolts and nuts to a heavy metal disc that has free-swinging metal flails that knock the chips out of the machine. To get at the chipper blades, you must remove the large plastic chipper chute. Easily done at the blade end, but undoing the metal arm supporting the chute is a bit bothersome. With the chute removed, the two blades are visible and can be removed by using an allen wrench from the chute side, and by putting an adjustable wrench up the chip outlet to hold the nuts. While the blades were easy to sharpen, one was never ground properly to begin with; it had a crescent shaped grind that left the blade end unsharpened.
The shredder blade was a major pain. It's shaped like a mini-lawn mower blade and held by a bolt at the center and a flush bolt and nut at each end. To get at the blade, you must remove the large drop down hopper with the small wheels. That chute comes off by removing six nuts, but the remainder of the machine must be supported by blocks. Then shredder blade is then visible and the center bolt is easily removed. However the two remaining bolts were more difficult. There's very little space to stick a wrench behind the metal disc/impeller to hold the nut while turning the flush bolt head with an allen wrench. Perhaps my bolts were overtightened originally; I ended up having to unbolt the metal clamshell that covers the impeller just to get enough maneuvering room to undo the two flush bolt/nuts.
Though sharpening the blades is a bit of work, it's very worthwhile. I suspect many problems folks have with chippers is because of dull blades.
The chip bag is a nice accessory. Chips and dust otherwise fly quite a distance, and they'll dig a small hole into the soil where they exit the machine. However, the small bag fills up rather quickly.
Having a push stick or tamper is a good idea. Tangled branches etc. can become stuck in the shredder chute, and branches in the chipper chute don't get pulled in by themselves. It helps to have something to push short branch pieces down into the chipper blades.
I chipped both green and seasoned branches. The engine had minimal slowdown on approx 2" dia. dry hardwood branches. I shredded leafy twigs and up to 1/2" dia. branches and had no problems other than an occasional clog while shoving material down the hopper. Some clogs resulted from twigs getting stuck on the oddly located metal pull-bar handle that's inside the chute. This handle is used to drop the chute to the ground so debris may be raked in. Other clogs were from twigs getting caught in a small opening near the blade where the chute is hinged. All were easily resolved by pushing the material down with a stick. I did not try shredding any wet or dry leaves (those I shred/collect with a lawnmower and bag).
If you plan on chipping prunings from trees with perpendicular branch structure(vs. 'v' shaped crotches) such as on some fruit trees, consider hiring/renting a commercial chipper. The relatively small chipper chute and 3" diameter limit requires you to prune off any side branches that are too large to bend aside.