Getting better for sure but still not an incredibly safe part of Panama to visit.
We visited Colon on a cruise ship, and it was a little scary considering that it's the only port we've ever visited (in ten cruises) that had a warning regarding the safety of the port. We took a cruise ship excursion through the town, which didn't look too scary near the cruise port, and we stopped at the Gatun locks.
The Canal zone is a great place for shopping especially if you're buying in bulk for resale.
Colon has the Free Zone, good for shopping if you have a passport and do not live in Panama. Must visit the Washington Hotel, see the church across the street from the hotel and see the breakwall.