A couple of months ago I bought a JVC KD-X250-BT. This turned out to be a very disappointing buy.
Although it connects with 2 phones at the same time, switching between them is a nightmare: you have to enter the menu, disconnect one and reconnect the second one. Only then you can start playing the songs from the right phone.
Entering the menu means pressing MENU for 3 seconds. And them carefully using a lousy volume knob (that always overshoots) to navigate the menus. And then you cannot turn the volume up or down before pressing RETURN for... 3 seconds. While driving.
Takes 20 seconds(!) to connect to the phone (Android or iPhone) and every time it connects to the phone it STOPS the music (it's called a Music Player, I call it a Music Stopper). Turn the engine off and on again just makes you repeat all over again: wait 20 seconds, press MENU (for play), enjoy your music. Argh...
Bluetooth is poorly implemented: pairing is cryptic to say the least, disconnects randomly and has a 3 second (!) lag on every function. Press PLAY... wait 3 seconds. Press NEXT... wait 3 seconds... Press RANDOM... wait 3 seconds...
It's a very poorly designed thing. Even JVC has better units than this one.
I've posted this review on Amazon: