It *is* backward-compatible, but now a freshly-introduced turns-out-to-be-big feature is missing.
Here I was referencing the "new" channels and super-groups, which still aren't implemented in telegram-purple, because Matthias hasn't had enough time for that yet (and I don't have any time at all).
This is made worse by the fact that Telegram released or intends to release a new feature: editable chat messages. This will cause even more problems, since libpurple sinply doesn't have any API for that.
Is anything happening here? Months passed since last email.
In short: no, nothing to see here.If anyone is willing to work on libtgl's (the vysheng fork) missing API for channels (which is the main thing holding up 1.3.0), go for it and implement it. Then implement 1.3.0. If you do that, I'm more than willing to help with the Debianization and maintain it for quite a while :P
Sorry. For now, you *could* clone and build from the github "dev-1.3.0" branch, if you keep in mind that support for super-groups and channels is incomplete (some messages may be silently dropped; some may be duplicated). Or just clone and build from master, which is stable (but doesn't support super-groups or channels at all).
Regards, Ben