Vocal Rider is excellent. I have been using it for a few days now. Firstly I think some prep is required on a vocal track that varies a lot in level. e.g. a young singer that is good but does not have a lot of control over very consistent levels. e.g. some of these teens I have recorded. I like to cut the vocal track into smaller sections and vary some of the gains of individual phrases and level them up as per Craig's article on the Presonus blog. I finish that off with a compressor doing light conditioning. Then follow it all with vocal rider. It just seems to level everything one step further. Its great for bringing up the ends of words and phrases etc. It is interesting to watch too.
Be prepared to fiddle with the settings though and you will need to tweak it a bit. e.g. the target level, the min and max ranges and also the sensitivity. If the sensitivity is too high it will bring up any spill in between vocals. But once set right it will ignore the spill and just ride the actual vocals.
On a pro track that has been well recorded it works even better. So much so you will feel like you don't even need a compressor on the track. It is quite smart. It is a plug you will use a lot once you get it I can almost guarantee it.
I have not even side chained it yet either just been using on tracks.