George,
Make sure you do a "search" on the forum for "smoke ring". We discussed this at lenght.
But I'll help with a short answer.
Most people grew up and were told that if there's a smoke ring, it's good bbq -- wrong! It's actually a chemical effect of nitrates/nitrites from the charcoal that actually "cures" the outer portion of the product. Since you're not burning charcoal or something like that, you won't get a ring.
One of the forum members in Texas said people didn't like his brisket because it didn't have a ring. Hard to tell Texans when they're wrong.
He added a chunk of charcoal to his wood box, got the effect.
It's all visual, not taste.
FYI, the BBQ circuit doesn't allow you to judge a ring because it can be chemically produced.
Hope that helps.
Smokin'