From my log book. Dove two 2 tank dives there in August 2015 as a newer OW diver. Water temps 84 deg. No exposure suit. Vis 30 ft. Dove AL80s. I booked all dives through Chicos Dive Shop which was fine for Day 2. See below.
Day 1: Booked Mariettas trip through Chicos. Put on a very large Vallarta Adventures catamaran cattle boat. Most of the 100 people were snorkeling or just going for the boat ride. The 8 divers were met at the site by a small boat and we did our dives. The dives were ok but the trip was long due to the slow boat and extra activities on the boat such as the singing and dancing. It was fun but not a dedicated dive trip so beware if that is what not you are looking for. Dove Las Montanas and Los Peratas. 35 minute dives to 70 feet with 50 foot average. Decent reefs.
Day 2: Dove Los Arcos with Chicos on their smaller catamaran. 8 divers + 8 snorkelers. Four of the divers were doing OW and we're with an instructor so the remaining four dove with a DM. Vis 30 ft. 55 to 60 minute dives to 70 ft. Nice spot. Reefs with a wall.
Saw eagle ray, turtles, sea snakes, green moray, spotted moray, striped moray, octopus, and a bait ball.
There is very limited information on diving Nuevo/Puerto Vallarta here or elsewhere. The diving was nice although vis is not what can be found in the Caribbean or SE Asia although I dive NJ waters so 30 ft to me is just fine, especially when no exposure suit is needed. I would return if I had to (i.e., as part of a family vacation) but not as a dedicated dive trip. I would use Chicos if staying downtown or look into Vallarta Undersea if staying in Nuevo who I found walking around a marina my last day there. Dive packages at Chicos are a few dollars less.