Other than some O'Neill-lite episodes, Season 6 is pretty much indistinguishable in quality from Seasons 1-5.
Seasons 7 & 8 aren't as fresh or as original as the show was in its prime but there's still a lot of great episodes there. There's also a lot of filler and a few episodes that are just plain unwatchable. *cough*"Avenger 2.0."*cough*
You might want to pick & choose which episodes you watch during this era.
Seasons 9 & 10 are very much a different show but still a really good show. I love Vala!
Honestly, even if the show lost half a step in its later seasons, the entire show was executed with a great deal of competence. It's not like the show suddenly took a total nosedive at the end for no reason (i.e. Earth: Final Conflict, Buffy the Vampire Slayer,
or the original Star Trek
). If you made it through all of Season 1, surely you can make it through the rest of it.