Having the same issue. Latest FW on my 150 (SN:TMA2L6401007751) and iOS on my iPad, as per Jun 2015. When starting the app, it connects and starts syncing. After just a minute or so, the connection drops and I have to kill the app and restart it. Mostly this works, but sometimes I also have to forget the bluetooth device and repair. Very frustrating. This have been going on since I don't know when. Perhaps 6 months at least. One thing though. Even when Amplifi app looses connection, all other apps like Spotify, Youtube or Music player streams music without interruption, so this seems to be either something with the Amplify Remote or something with Bluetooth Rx from the Amplifi 150.
About my 150: I am really happy with the design, the editor and the sound quality is really good. HOWEVER, what I'm not at all satisfied with is the app itself. 1. The presets available are mostly terrible and far to low leveled to be of any real use. Hopefully we will see a lot of useable presets in the future. 2. The app forces a preset switch when you select another song even if you are completely happy with the preset you've selected before. 3. Mostly you will not be able to choose among your own presets while at the play mode, but have to go back to the main menu and select your preset from there. Every time you switch song you are forced to to the same if you want to use the previous setting. 4. Many songs are not recognized and you will therefore not get any suitable preset listed. 5. Slow connection to Line6 cloud and tone matching are therefore a bit too lagging. So my main concern is the app, that I think needs to be completely remodeled to become usable. Luckily for everyone, this is something totally possible.