I think Android app compatibility is necessary for a Linux phone. You won't be able to use Play Services, but a lot of apps do not require that. Android compatibility would for instance give you WhatsApp. It also gives you access to hardware like activity monitors (Garmin and Withings apps don't require play services), which otherwise is very unlikely to be supported. And also sophisticated public transport apps like Moovit.
http://arstechnica.co.uk/gadgets/2016/05/chrome-os-android-a...
I have many gripes with my Ubuntu phone, but this isn't one of them. Aside from my personal preference of opting out of Whatsapp, they do have the webapp version so you don't need to carry that Android around once registered.
They also have Signal, which works well. I SSH/tmux into a box with command line Finch (pidgin for CLI) and IRSSI when I really need to IM 'on the go' and I don't have their number for a message. Which is a rare situation.
About Signal: especially now that Whatsapp has adopt their encryption protocol, it is very hard for me to convince everyone else to switch to Signal, and AFAIK Signal does not do group messaging, so I would have to convince other people to switch to an inferior solution with no extra value to justify the tradeoff. If I had decent XMPP/SIP clients I could at least try to sell the extra value of having your communications outside of control of any single company.
The software they have is great, and I haven't seen any half-backed features. The updates are consistent and always bring something interesting. The idea of lenses and scopes are great as an alternative to the lack of common apps. I didn't miss not having a weather app or yelp, or youtube or whatever.
The one thing that is lacking on Ubuntu Touch are the things that are core to mobile use cases. For example:
- I understand that I won't get a decent Google Maps app, but there is no real alternative. Here Maps comes installed, but I could not find a way to get public transportation data. uNav seems to do the turn-by-turn navigation, but they don't have voice, which is useless when I am on a bike.
- There is no decent story for messaging/VoIP: You can have Telegram, but also is just a webview wrapper. Messenger, Whatsapp? Nothing. And if at least they had half-decent XMPP/SIP clients, I could try to drop the closed services and try to switch my friends and family with me. But what good is a smartphone that I can't use to talk or chat?
Because of these things, I was basically forced to always be walking around with two phones: the Ubuntu one for connectivity and basic media and as a hotspot for my broken Android, which I would then use when I needed to look into maps or call/message someone. The hassle was enough for me to find a replacement board for the SIM card and go back to use only Android for everything. The Ubuntu phone now is in a drawer, waiting for me to get some time to play with application development for Ubuntu Touch.
All-in-all, my feeling is that Canonical is close to get its break and make Ubuntu a compelling alternative. It is just not there yet. I also hope that this Moto G was my last Android phone.