Pros: Cheap beer. You can get $1 and $2 beers at the OXXO close to the marina.
Fun bargaining. There's a lot of vendors to bargain with - even the companies who have water activities.
If you are a geocacher there are a few to find here!
Cons: Dangerous waters at Pelican Rock/Lovers Beach. It's beautiful and you can see tropical fish. Our boat driver questioned our decision to spend time there with the kids. We thought we would be okay since we live in a beach city and go to the ocean practically every weekend when it's warm. However, we almost lost our 6 year old after a huge wave knocked her off of a rock and sucked her into the ocean - I almost went along with her while trying to help. Luckily my husband was able to save her and a few men were able to help my husband back on shore. After that incident we saw 3 more people get pulled out on the water, with one guy having to be resuscitated. Medano beach is much more calm, I've heard.
Not much to do with young kids. It's more of a party-atmosphere.