The updates we're particularly interested in are those for the 920/925, the 1020, the 930/1520 and the 830, all of which have potential from some 'secret sauce' to make use of the hardware, especially imaging. But we're still waiting for each of these models, so watch this space.
In the meantime, we'll all have to be patient. You can also manually check for the update by going into Settings –> Phone Update –> Check for Updates, of course. As good preparation, make sure that you have 2GB of internal storage free (I can imagine this may cause some people problems) and that your device is over 50% charged, since the update won't start if the battery if drained below this stat.
The Lumia Denim updates for the budget devices do still bring new capabilities under the hood, though I doubt most users will be able to tell the difference. From 'Hey Cortana' to the Lumia Camera 5 tricks, almost everything user facing requires higher end hardware. As I say, watch this space.
Curiously, the update page (for Europe) linked above is not matched by similar pages for other markets at the time of writing - no doubt there's work still going on in Microsoft's web team to apply similar layout and info to other continents.