I have a Jolla (Sailfish) phone. I can not use the web client, because I need an Android, Windows or Blackberry phone. WhatsApp does however work fine on my phone (via Alien Dalvik).
This "web client" is not actually a web client - it's just an app for your phone that you can display on your computer monitor.
Sailfish itself is much better than anything I have ever used - it's clearly designed for touchscreens. For hackers it's awesome because it's actually a Linux, and you can access shell (as a root, too).
Android support is a bit buggy though - for example Skype sometimes breaks (can not send messages), but Spotify and WhatsApp have worked perfectly fine.
If you are interested in it, they dropped the price a while back (down to 250eur).
The interop with Android works great. Spotify, HN App, reddit is fun, YouTube, Google Chrome and Google Play Store(!) work without problems except for some crashes from time to time.
The only problematic app is WhatsApp because the notifications only go into the native Sailfish notification area when an Android app is in the foreground.
Many apps and copy&pasting between native/Android apps were fixed in the last Sailfish version released 3 weeks ago.
This "web client" is not actually a web client - it's just an app for your phone that you can display on your computer monitor.