According to the Vineco salespeople that I was dealing with when Vinterra was announced, the Vinterra brand is just below Ken Ridge Showcase in quality, TDS, etc. The product is a kit (not a juice product like Tom and djrockinsteve mentioned) and was created partly for a chain of stores in Ontario. It allows folks living in areas of dubious water (think Walkerton Ontario) to make a kit without adding any tap water, and is said to be very popular in some areas.
I was told that Vinterra kits are mostly juice with some concentrate, and that the amount of concentrate varies from batch to batch to allow for seasonal differences in the juice. According to Tim V of Winexpert, adding an amount of concentrate to a juice kit provides considerably enhanced shelf life.
From my own experience, I know that the Shiraz, Merlot and Pinot Grigio are very good. There is a pail of Vinterra Shiraz in the my basement that I had expected to start at the end of the year or in early January but plans changed. Probably get it started in a month or so. This Shiraz was directly responsible for my FoP getting 2 or 3 new customers.
Spagnols has two similar products. Bolero is better than their Grand Cru line but not as good as their 6 weeek kits. Not sure how it compares to Grand Cru International. Their Premier Cru line was added after I stopped being a retailer but I believe that it is roughly the same quality as the Vinterra, so better than regular Cellar Classic and not as good as Cru Select.
PS these kits are available year round not seasonally like the juices mentioned above. However some retailers that I have met only seem to order them once a year.