Taste; Can't really say much as it's a multi-vitamin, but no bitter aftertaste as I have had some in the past.
Effectiveness: I always take multi-vitamins if i'm in a calorie deficit, seeing as I get sick easily when i'm cutting, so I need to pack as much punch as possible with immune system. So, if I take this, i'll usually take fish oils, etc. so I can actually measure my body response to a stack. It's usually the same product line stack too. So I was impressed, no illness with my cut, and I wasn't as worn-down as I get when i'm dropping weight mid winter.
Overall: A fan of optimum nutritions line. Aside from the B.S. marketing a lot of sup companies make, they've done a pretty good job at providing quality products. You do pay for the quality you get, so from my experience, I tend to trust these companies to do the job effectively. That being said, I do think that other companies in this space do just as good a job in bring out quality products.
Bottomline: Buy if you have the cash and you're looking for a top of the line type vitamin.