Opus all have a very characteristic taste; but within the cigar line, each vitola is slightly different. The "A"s and double corona's tend to be milder, despite Fuente spicing up the blend recently. This is fairly normal for larger cigars; despite being intimidating looking, they are often milder than smaller cigars that burn hotter and have less tobacco for the smoke to go through.
I will say this, like any other cigar, how Opus have been cared for makes a huge difference in the taste. I've had sticks given to me that tasted like ass; could barely recognize the Opus taste. Somewhere along the way, they must have not been treated well. I've also had sticks handed to me by people who work at Fuente, and despite being years old, they taste absolutely incredible and full flavored.
Opus are aged for a year before they are shipped, but even so, they tend to be oily when young; that means they may burn uneven or require re-lights. Fresh Opus also tend to be rather strong/spicy -- a well cared for Opus with -23 years of age is optimal, IMHO, just like many Cubans don't hit their stride for a few years.
I pick the vitola of Opus to smoke based on how much time I'll have; the smaller ones when I don't have that much time to invest, or want a stronger smoke.
Hope this helps...