Good for a while...then a flash popped and ceased to power.
592658
I've had this 2 flash set for almost 1 year. It is my first set of speedlites and they've performed well. Well, until about 2 weeks ago. One of the speedlites popped loudly while using and ceased to work. I believe the flash blew or an electronic component overheated and blew. I'm still using the other flash without any problems. I'll be looking to upgrade to a better brand in the very near future. However, I cannot recommend these flashes unless you're on a budget and a beginner.
1838437
As many have alluded to, this is a great flash if you don't get a lemon. Flash worked for approximately 100 flashes and now only turns on without any bulb action. I have troubleshooted everything and the only answer is the flash is faulty. In terms of customer service, I have tried to reach them for over a year to return the product or get an answer with no luck.
798412
This is my third Yongnuo flash - my first with the receiver built in. It worked for one photo shoot, then decided to stop working a couple of months later. I thought the batteries might be dead, so I swapped them out with brand new batteries but the flash still didn't fire. Quite embarrassing to say the least since I had just started the shoot.
4810979
This was working pretty well for me; I purchased this late December to use in conjuction with my Canon 80D to make youtube videos. To give you an estimate, I try to turn out one video per week. I don't know what happened but I was using it a few days ago and a lot of a sudden I heard a pop. I had no idea where it was coming from, the light was still working just fine. I heard it again about 5 mins later, and then I heard a sizzle. It sounded like a bottle that was filled with liquid had burst and the liquid was oozing out onto something hot. I still wasn't sure where it was coming from, the light was still on. I turned the light off and put it away in my camera bag since I was finished using it. I looked at my hand and it was wet, I looked at the spot on my dresser where the light was sitting and there was drops of mositure. I took the light back out of my bag and it was leaking. I opened the battery pack and the batteries looked like they had eroded. I had just put those batteries in about 3 weekds prior. Once I let all the liquid drain out  I put the batteries back in to see if the light would come on and it was very dim. I tried the next day and it came one like nothing was wrong, now it's completely out. I don't know what happened, but it's no longer working.
4949327
I've had this camera for just over a year, and it worked well, while it worked; but on vacation last week, the flash broke. I'd probably try a different brand if you want a waterproof camera.
4568594
I purchased this flash because of the great reviews it received.  While using it I never had any problems with it.  While out on an on-location shoot, it stopped flashing.  It still makes the sound as if it does flash but no light.  Very disappointed with this product.
2761000
Served us fine for a bit over a year, and then started sparking and popping and and shorting out, even when empty (before you reply saying there's metal in it). Discarded and now looking for a replacement. I guess for $60 one doesn't expect TOO much, but I do expect more than 18 months of use!
496147
Read all the bad reviews about this flash and thought I might get lucky and receive a good one. Well it was nice while it lasted but now it will not trigger while on any of thee cameras. Pilot works though. Look elsewhere.
3265303
Seemed to work fine initially. Was checking range one day and was impressed that they fired from almost 100 yards. Changed receivers and got similar range with the other but then the flash started firing on it's own randomly. Moved back in range and it stopped but later started doing it at close range. Not good for flash life or battery life. Guess I only got 1 good receiver with mine.
3669804
while it lasted, I had this for quite awhile now. though it's a great flashlight, it does get warm during used. Also, my switch no longer work properly after i drop it a few time. Now i have to smash the switch repeated until i able to turn on the flashlight, even then tiny movement would make it automatically turned off most of the time, or switch to every other modes.
958244
it was a pretty good bang for my buck until it decided to just stop working. i will take the bad review down if i get a replacement, but it seems like i was given a defective item :(
2571660
Good while it lasts.  For a year, these were great.  worked as desired and was nice to have flashlights handy throughout the house serving dual purpose as emergency light in case of power outage.  I used to own 6 of them.  Unfortunately, 4 of the charger bases have since quit working so I now rotate the flashlights through my remaining 2 bases that work.  It's a great concept but in my experience, these were not made to last.
451841
Faulty casing isn't the only issue with this thing.

The flash memory started dying after a few months; too bad it doesn't have SMART status as I only noticed it when my file manager started reporting less and less available space on the device. The flash nodes in this thing are dying like a herd of diseased cattle! Lost a huge LaTeX file thanks to this faulty device, too. What a shame.
3701822
Worked for a while, then quit. Not sure what happened, but I think it was a software issue if anything.
1719798
the picture quality was amazing while it worked. However less then a year or just over a year into owning it and using it sparingly it randomly just stopped working. weird.
4632788
mine stopped working after 6 months , this is a use and throw flash light , i had actually purchased 4 of these and all of them stopped working after 5-6 months
2088009
I live off grid in a solar house.

I have 4 of these. One in storage and the other three in use. I've been using them for about a year - alternating between the units as the weather turned dark (I live near the Canadian border in the Pacific Northwest). For the first three or so months, all worked as advertised - they were bright, dependable flashlights. All they needed was to sit in a window during the day to get charged up for the night.

Each light got about an hour to two hours of use twice a week.

As the months went by the malfunctions began - one began to strobe and/or flicker bright and dark. Add a month or two and one lost about half of its brightness. Wondering if they needed more solar charging, I tried, repeatedly, to charge these units in full sun or for several days in reasonably good light to no avail. The problems continued.

On the plus side, these are inexpensive lights that work well for a limited time (in my experience); but may not be reliable in a survival situation.

Until they improve I'm considering different alternatives.