We purchased one of those cheapies off ebay, it went okay but if we had bought properly the first time then we would have had an extra $120 in our pockets.
We bought it primarily because it was only going to be used lightly, cut up fire wood while camping, a small backyard tree or two (nothing over 15cm thick) ect At first it cut okay, always cleaned it up and maintained it before and after use, the chain didnt sharpen up very well and after a year of light use it started leaking oil. We were looking at getting a new chain and at over $50 for a new one coupled with the excessive oil leakage decided it wasnt worth it.
We ended up buying a stihl chainsaw that was on special, havent looked back. We have since cut down 9 trees in the yard, plenty of firewood, some of it as hard and concrete and it works a treat, chain sharpens up nicely.
Compare our camping trip last weekend where the guy who had the ebay saw needed us to cut his wood for him because his couldnt cope with the aged wood on the tracks and using the same tool (we forgot ours so used his) couldnt sharpen up his chain, while it sharpened ours okay.