IME it's all down to the implementation these days, which is a low-bidder-gets-what-they-pay-for kind of affair. My phone is cheap and the Bluetooth is nearly unusable on it(it can only really support one device at a time and that device will periodically drop out), but on my laptops, which have more of an emphasis on build quality, it's pretty solid, with few to occasional instances of audio tearing.

Regardless I still find grief from things like the volume resetting on one or both ends after pairing. There is a lot of attention to detail needed to get this stuff right, and most companies can barely manage to ship - that's not on the standard of the spec but the standard of the marketplace.