'Disclosure' is the poorest episode to date. Only of interest to those who are totally unfamiliar with Stargate's earlier seasons.
'Forsaken' is OK, but it becomes ever clearer that scripts are still being written for "Dr. Jackson", rather than "Jonas Quinn". In general, the personal interaction that made Stargate's 2nd through 5th seasons so special is missing in Season 6.
The Changeling' will be fine for Teal'c fans, but isn't anything special.
'Memento': the best episode, by far. And the only reason I didn't feel the disk was complete waste of money. Good storyline, and it introduces more facets to the Stargate universe with the crew of the ship.