I have a grow going with them right now (sig) to determine whether I'll use them for flowering going forward. Well documented and in a stable environment. I have 5 of them and they definitely have a place in my clone/seedling and veg cycles, just not sure whether they can flower to my liking yet. I had a lot of other environmental issues in past grows and was not happy with the outcome but the lights were not the blame/problem, I was.
My 2 cents on the LG or any chinese panels: They're all risky, if you're willing to take some risk there are some that will be fine for a hobby grow or to get a feel for growing with LED's, they are quite different than growing with more traditional lighting. For the price, for a hobby grow with no pressure to produce, I would recommend the LG's for vegging right now, flowering will be determined in about 8 weeks when this round finishes. From a quality/reliability perspective, I've had 5, a couple running for 6 months + almost constantly, have not had a single problem/break/failure, other than one had a loose hanger screw which was tightened easily enough and had no affect on performance.
Are they the same or as good as some of the established brands? I'd say no, if you want proven results and little risk, go with an A51 or Hans.
Do they provide decent value for the price? I'd say yes, the price is low enough that a couple of grows would more than pay back initial investment. They're also priced low enough to have a spare on hand.
imo, there is no right or wrong on this subject. It all depends on the level of risk you're willing to accept and whether your typical buying habits are to go with brand name/established brands vs. taking some risk on knock off's. No different than buying a car or any high ticket item. You can buy a car new and pay for it, you can buy used an take some risk but save a ton of money. I personally have not bought a new car off a dealer lot for 15-20 years, I'm willing to take some risk and have done quite well buying almost new, low mileage, second hand cars and motorcycles off auto trader and kijiji. Personal choice imo.