I even managed to transfer old school photos off my ancient 2003 NEC flip phone to my current Android phone even though the former uses Bluetooth 1.1 and the latter 5.1. I also fondly remember using Bluetooth in school to transfer ringtones and wallpapers to that phone from my Windows XP PC, or to and from other kids' phones and it always worked.
Maybe I was really lucky, but for all its apparent faults Bluetooth has always served me well and I personally can't really fault it for its intended purpose.
As former SDR developer who dived into Bluetooth firmware at some point, I can only attribute the connectivity issues some Bluetooth devices have to just poor firmware design with insuficient testing, or most commonly, bad antenna design with insufficient real world testing from the device manufacturer (experienced RF graybeard engineers are expensive $$$, and most HW companies are sweatshops who pay their engineers peanuts, so there's the main problem that leads to the infamous Bluetooth connectivity issues IMHO), and not to issues with Bluetooth tech itself, fact confirmed after lengthy discussions with our HW guru in the lab. From my experience Sony, Bose and Panasonic put great thought into antenna design while Samsung and LG can be pretty hit or miss. I have not looked into Apple's though, so I can't say, but from the rest of their HW design and the talent they usually have in the HW department, I can assume it's top notch as well.
The 2.4GHz spectrum is way more crowded today than it was in 1999 when the first Bluetooth version came out, so getting uninterrupted real-time audio streams reliably on it is hard, but not impossible.
One thing I can fault the Bluetooth SIG is that the spec is very complex and full of optional bits which could lead to many pitfalls for the uninitiated engineers and worse, gives developers too much freedom in implementation, meaning your widget might not play well with another widget because each took their allowed freedom in different directions, though Bluetooth chips from reputable manufacturers who know what they're doing, like CSR, TI, SiLabs and Nordic are nearly bulletproof in this regard, provided you also do a good job on your antenna design.