So a few things seem to have changed. I'm not sure it's all an improvement, and I think some of it may be unintended. In particular, the interaction of solo selections between the track pane and the bus pane seems to have changed.
 
Take the following scenario I ran into earlier. I've got a bunch of drum tracks, and they all have sends to a drum reverb bus.
 
I solo all the drum tracks, so I can listen to the drums alone. I can hear the drums and any buses they're feeding. So far so normal.
 
I then decide I want to listen to the drum reverb alone. I solo the drum reverb bus. Nothing changes; I can still hear the drum tracks as solo-ed in the track pane. I have to then un-solo those to just hear the bus.
 
This is new, isn't it? It seems a bit cumbersome. I'm sure it used to be possible to do what I'm trying to do. Have I missed a setting somewhere?
 
 

That is intended. The prior behavior was unintended - or at least it didn't matter that much before aux tracks :)
Now that we have aux tracks the behavior of bus and track solo needs to be consistent. i.e if upstream tracks are soloed they need to be audible even when a downstream bus or aux track is soloed. 
 
If you want to hear only the reverb bus in your scenario, you shouldn't keep upstream tracks soloed. I understand that it didn't require this earlier, but this change is necessary to support patch point solo more consistently. Hope this explains why....

Yeah, I can see how it makes sense for consistency.

I ran into this last night too John. Makes sense in the big picture of Noel's explanation.  A couple of days and we will forget the old behaviour I guess:) 

Yeah, not a big deal. Minor change of habit.

Can you just do "Exclusive Solo" on the reverb bus - I am not at my DAW but it would be interesting to see if that works without have to click loads of solos on and off?

The exclusive solo is conditional to the track type Boydie, so enabling solo on a bus with it engaged will not disengage whatever tracks are soloed.
 
No issue though. Already used to disengaging the track solos before soloing the fx bus. Also yet another good reason to use track folders:) 

I prefer it this way.
 
In your original scenario John, it's just 2 clicks - one to disable Global Solo in the Command Bar and two to solo your reverb buss.

Noel Borthwick [Cakewalk]
That is intended. The prior behavior was unintended - or at least it didn't matter that much before aux tracks :)
Now that we have aux tracks the behavior of bus and track solo needs to be consistent. i.e if upstream tracks are soloed they need to be audible even when a downstream bus or aux track is soloed. 
 
If you want to hear only the reverb bus in your scenario, you shouldn't keep upstream tracks soloed. I understand that it didn't require this earlier, but this change is necessary to support patch point solo more consistently. Hope this explains why....

Hi, Noel. Have you considered incorporating a modifier key, so that, say, Ctrl+Solo would achieve what John is trying to do?

benjaminfrog
Hi, Noel. Have you considered incorporating a modifier key, so that, say, Ctrl+Solo would achieve what John is trying to do?

I think a better approach could be to make exclusive solo be independent of the bus type. Or at least have a mod key to do so. i.e if you exclusive solo a bus it would unsolo all tracks and only leave that bus soloed. 
Overall the new solo mechanics is more robust and consistent than what it was in earlier versions and several corner cases and bugs were addressed as well.