Great! I've been using Signal for iOS and while it's not yet comparable to WhatsApp feature-wise, it's for sure good enough to use.
I find it very difficult to get people to switch from the walled gardens of iOS messaging and WhatsApp (WhatsApp dominates the Dutch market for interesting historical reasons). I've been able to get a handful of privacy conscious friends to switch to Signal/TextSecure, hopefully the cross-platform branding makes this a bit easier.
You can run your own server, but there's no federation.
The reason for that I imagine is that they want a privacy preserving automatic lookup method (a single server can confirm phone numbers and allow privacy preserving contact list comparisons for its own clients), and aren't convinced of using a model where the public key is the identifier instead of your phone number.
Have you actually tried it, or do you know somebody who have tried? Is the client really fully independent on Whisper servers? Can it work without the mobile connection, just with WiFi?
Does the voice communication work?
I'm asking all this because it seems that the server code was earlier in "you can look but it's not enough to run it" state?
I've run the server source as a private textsecure chat app. You can run your own without the proprietary gapps framework app too by mimicking what GCM does on your own back end, and it works with wifi if you change the identifiers to email/nicks instead of phone numbers, but this was for a small number of coworkers nothing of massive scale. This was for business communication from China since at that time TS wasn't working very well behind the GFC but they added another server around that time (I assume, all connections got better) so we abandoned our hacked fork for regular TS/Signal.
I have read of people on the mailing list who appear to have the server running.
There used to be some documentation about running it, but it was removed from the repo (presumably because they didn't want to dedicate resources to supporting it, but that's just a guess).
I find it very difficult to get people to switch from the walled gardens of iOS messaging and WhatsApp (WhatsApp dominates the Dutch market for interesting historical reasons). I've been able to get a handful of privacy conscious friends to switch to Signal/TextSecure, hopefully the cross-platform branding makes this a bit easier.