First off, I REALLY like these, they work well, easy to use, look nice, clear sound, recharges easily and have not run out of batteries during a gig as long as I charged them beforehand.
So why four stars? Just a couple of issues

Occasionally I have found the channel has changed from one use to the the next on the receiver. Easy to put it back, but I shouldn't have to, as a pro musician I just want my stuff to work, every time. I wrote the mfg to see if this is a common problem or if I'm doing something wrong, which may be possible, but I have yet to hear back, there should be better support. Concerns me if there's a serious problem

I have tried these with a number of guitars and basses, passive and active pickups, no problems EXCEPT with an Ibanez bass with active pickups, I was getting a high freq. sound when plugged into the bass, apparently the transmitter does produce a little audible range RF noise which was being picked up via the wires next to the 1/4 jack on the bass, also picked it up putting it next to the actual pickups, and separately on a Strat pickup. Problem easily solved by having it just few inches away with an extension cord. They do say not recommended for active pickups, so this is not a complaint, just be aware of it.

If you're tired of tripping over your cord in the living room or on stage, this is what you need. The USPS shipping sucked; I'll leave it at that. But I have had a blast with the Xvive. Just stay away from your Wi-Fi router. The reason I think some gave it a low score is because they didn't read the directions. I couldn't be happier with it! I've ran it through an SG, Les Paul and a Gretsch with no problems at all. I've played it in the back yard, garage and kitchen and never lost signal. Sure it pops every now and then, but that's because of my WiFi signal. My git buddies have this on their wish list. Great Product!

When I use the u2 at home where there is wifi I get a little interference nothing to bad my mixer is on top of my desk wher ther is about 20' away from my wifi router but if I use a guitar cord and put the receiver on the floor under the desk I don't have no problems works fine .
I play in church band where the wifi is a far far away so absolutely nave not have NO interference witch is nice . I use the u2 before the effect pedal and after the effect pedal with no change of sound just love it hope it last for a long time love being free from the guitar cord

Great product at an affordable price. Size and former factor are perhaps best out there. I did have some slight interference next to a WiFi router first time using it playing electric guitar . I play it in another room generally with no problems 97% of the time. No lag that is noticed but 3% of time I got slight momentary interruptions in signal. I even played it through walls in another room at least 35 to 40 feet away and still worked. Hopefully the performance lasts. Best part for me is the ergonomic design.

This Xvive Wireless Guitar System is just what I wanted ! The sound is great and I can't tell the difference in audio quality between being plugged in by cables or this receiver / transmitter system. They have 4 channels to use so different musicians can use the same Xvive and choose different channels and play away. Being rechargeable is another plus. Great Buy !!!

I highly recommend Xvive U2 !