I purchased the Harbor Freight one last year. I have used it often on 3 chains, in rotation, on my 455over the course of 2 years, and over 30 cords of wood. It does the job a $40.00 grinder is designed to do. I now hand file all my chains, and have had better success on initial sharpening, and holding an edge. There has been a number of times that grinder has saved me from buying a new chain, or taking it to a shop, just to have them grind half the cutter out. If you get all the cutter heads goofed up, i.e. hitting a rock, or nails, the grinder is the silver lining. The only complaint I have us that it seems to heat the cutter head up a bit, untempering the metal, making it loose the edge faster. A good file and allot of patience will reward better that a cheap-o grinder. But hey, I have one, so...
Another helping point in helping the novice sharpening experience is to get a round chisel, or even a chipper chain. The full chisel is sweet, but only on clean wood. The round chisel will hold an edge for allot longer before needing a freshening up. I have seen a bid difference between the 2 kinds, and will lean towards the round chisel on my 028 when there is any question of what the wood has been laying in or the condition the wood is in.