Yes, they strictly block the aisles while at-bats are going in. Not sure how many other MLB ballparks still do that, but I greatly appreciate it.
I think I've been to 17 active MLB ballparks, Petco is definitely in the top-5. Has the feel of a spring training park blown up to full size. The biggest negative is that the fans also seem to have the "spring training" attitude and haven't shown much knowledge or interest in the actual game, but the two games I went to were mostly duds and I wasn't in the prime seating areas.
Honestly I've had bad luck with MLB games this year, been to about 10 and all were mediocre to bad -- but I think that's mostly just the product that MLB is right now. There are less than 50 legitimately good hitters left in MLB and everyone else is getting blown away by the 98+ mph pitches and praying to get lucky and hit a home run.