We visited San Francisco for 4 days during September 2004.
We found the Pier 39 area to be quite stereotypical of an over developed tourist area, with its cheap knock off souvineer shops and over priced restaurants, but we would still encourange anyone to visit it at least once. Those with a good experience of these type of attractions will know you can no doubt score a good bargain or meal if you look for it.
We knew we had to come to this area to catch the ferry over to Alcatraz, and would advise that you come early, as the line up for tickets can get quite long by late morning, and the daily tours seem to sell out around lunch time. You can't come here without experiencing Alcztraz!
The nearby sea lion colony is pretty cool and good for a laugh at the sea lions antics.
Be warned though, this is not an area to not be mindful of your valuables. Several times we spotted "locals" (two in particular who seemed to be regulars) clearly staking out people flaunting expensive cameres or other items. Beware of teams of two which seem to operating on the basis that one distracts whilst the other gets up to no good. Be wary of those that approach you with what seems like strange comments/requests - for example, one of the regulars we had observed earlier approached me and asked if I would like a shoe shine. Pretty stupid request considering I was wearing a pair of old sneakers. However, those with the usual street smart should have no problems in this area.
This review is the subjective opinion of a TripAdvisor member and not of TripAdvisor LLC.