I'm pretty sure the lost in the city with no memory story has been done to dust, and I haven't really liked these 'Trust' episodes with yet another Goa'uld crime lord on Earth (I mean why don't the police just carry around Naquadah detectors - all the criminals would stand out a mile!) but I have to say I thought this was one of the better ones. Mainly, that was because Vala was allowed to let rip and just be Vala (or was that Val). If you lost you memory and were told that story about your past you would not believe it.
My only problems would be in them having waited so long, and watched her so closely, yet they kept her in a known Goa'uld safe house. Very poor planning. I also thought that the SGC so easily dismissing the existance of the artifact, and Vala regaining her memory instantly at the end weren't credible.
Yep, an episode with good acting, nice locations, very little else.
It wasn't the worst episode I've seen, but it wasn't anywhere near the best. The whole story could have been done a lot better in my opinion and it took too long. I spent most of the time waiting for something to happen, which took until nearly the end of the episode.
Still, you have to have some duff episodes once in a while to make the good ones seem that much better, and after 10 years it is difficult to be consistent.