I've had this set for around six months so I've had plenty of time to get used to it.
Now, with the Play sampler upgraded to 1.1.6 and running very nicely in SONAR x64, VOP complements the other instruments in the EWQL stable nicely.
It has five voices, America, Wales, Syria, India and Bulgaria. All voices are recorded with two high quality mics, and you can choose whether to use one or both in your rendering. However I found that the right hand channel, was generally quite noisy and so I normally stick to the left.
The America voice is full of oohs and aahs, and makes a nice sound for people who want something ethereal and 'white'. Wales is a wide repertoire of vowel and consonant sounds, with some words built that one could use to build nonensical sentences with, but the keyswitch articulation programming means that you spend a lot of time scratching your head to work out where to put the switch notes in your piano roll. What it lacks is a word builder like Symphonic Choirs, and certainly nothing as versatile as Vocaloid - although once you find something you like the finished result always sounds a lot better than vocaloid.
India contains a lot of phrases in microtonal scales, so it's very hard to get to use that material in anything other than modular work. The lady who sings the Bulgarian material has a beautiful voice. But the one I like the most is Syria. The texture of this singer's voice is magnificent and rich, and she sings lots of nonsensical phrases that sound arabic in nature and make for a very exotic sound that might easily accompany another Ridley Scott ancient world epic.
This is the kind of product that you write material around, rather than try to squeeze into something that already exists. If you walk into it with that attitude then there's a lot that VOP can offer.