The (Temporary) changes I made to the top end of the M42 and A42 finally went live at the end of last week, so I drove them this morning and will again on my return trip on Wednesday so finally I can comment with authority on what my thoughts are;
Using the "City" field for junction number
Now I've driven routes with this I place I think it is a very bad idea. Not only is it bastardising the city field for a purpose it was never designed for in practice it doesn't work well.
The A42/M42 J10-14 and M1 J23A/24 have both POI's and the city field used for the roundabouts and slip roads, yet when navigating along the road, you only see the POI's unless you force Waze to zoom in:
In this one the POI is shown:
Here I managed to get the "City Name" to show (note the text is the same size as road names):
Additionally, when reporting events, it does tell you that it's close to the "City" if you are really close:
But otherwise it looks for something bigger even along the sparsely populated M42 area:
Slip road naming
I'm still more on the fence here. What I will say is that I totally agree with faitaru in that when I navigate or give directions on a motorway (or major road like the A1 and A42) I always go by junction number.
I'm not keen on the "to M1 (S)" convention, however to my surprise Waze's TTS announces the turn below as "At the roundabout take the second exit at A1 South" so the "to" is not used:
Additionally my (over the top) routing on the M42 (S) J10 exit shows that even in landscape mode there's not really enough space for much more than we're using now. Here (I think,would want to check again) that the TTS announces "Jct" as Junction, however in this example he's barely finished the 0.5 mile renouncement than I was at the turn!
So what do I think overall? Keep more or less what we have now, but perhaps we could adjust exit ramps to add road numbers e.g. "M1 (S) J23A to A42" or "M1 (S) J24 to A50/A6/A453" or similar.
I'll be restoring the M42 later (or more likely tomorrow) until we come up with a definitive answer.

