IMO, yes, in that it prevents vapor from entering through the block. It's not a vapor barrier in that moisture will collect on the 'side' of the barrier that's facing the LIVING area. Remember, when the relatively warm air of the basement comes in contact with the cooler wall, condensation forms regardless of whether you have Dryloc on it or not.
A recent issue of Fine Home Building Magazine recommended that vapor barriers NOT be used, and that a slight 'alteration' to how basements are finished be implemented. Essentially, you leave an air-gap of a few inches between the wall and the studs (when you frame it out), and then insulate and drywall as usual W/O a vapor barrier. What little vapor there is that permeates the insulation and drywall should be allowed through. The way you compensate for the moisture is to finish your basement WITH a dehumidifier. In short, let the moisture in but take it out with the dehumidifier. By 'trapping' vapors, well, there's potential for mold, mildew, standing water, etc., etc.. More and more, I am, personally, hearing of basement finishing being done this way.