The bars are junk along with most any other bar out of china. If it is a laminated bar, and it comes from china, or says "Australia", but not "Made in Australia", it is very poor quality: the sprocket may not stick far enough out of the nose laminations, the gauge will likely be highly variable down the length of the bar and usually 2 gauges too wide, the laminations or bar rails may be misaligned, and the steel may not be hardened properly, often chipping severely on the rails towards the nose.
Chinese chains usually function well, but may not be the fastest cutting. Archer chains seem to hold an edge for a while having hard steel and thick plating similar to Stihl, but they are slower having too tall of drive links that cause much extra friction with the saw chips.
How long does a Farmertec bar last? Well in my experience- you are going to get two kinds of answers regarding anything Farmertec- those that have bought them because of the price and will sing their praises regardless of the fact they have hardly seen enough use to fill a couple of pickup beds worth of firewood- or those that pretty much despise anything chainsaw related that comes out of a country that has a flag of red and yellow stars.
The newer solid bars with the clear coat finish look better than the earlier grey painted ones and look to be a direct copy of Sugi Hara bars- so at least there are quality tip replacement options, but if I look at their current pricing, do the exchange rate, factor in shipping- they are not much cheaper than genuine Sugi Hara bars here, for the 24" plus bars.
Old story, no such thing as a free lunch and you get what you pay for in most instances. If you want an occasional use longer bar, not likely to see much work, or a stumping bar- might be worth a punt.
I disagree because they don't even meet the tolerance requirements for a useable bar: Out of square rails, and a gauge .015" larger than the chain. You might get a good one that will last a gallon of gas worth of cutting, but not much longer without struggling with crooked cuts and chipped rails. That's just my experience with 3 different brands of chinese bars including farmer tec.