I enjoyed this show for two reasons 1. Richard Dean Anderson 2. Amanda Tapping. These two performers carried the show with able support from the regulars and recurring actors. The replacement of RDA in seasons 9-10 was enough to take the heart out of the show.
The chemistry between all the main characters is just tremendous. You get the feeling that the actors like to pal around after the camera stops rolling. This relationship carries over into the program we get to see.
RDA gives his 'O'Neill' character believable personality. He never knows when to give the wiseass in him a rest. You watch the others roll their eyes in dismay at some of his utterances. Still, they know that he is the man to have around when the situation is perilous.
There is a lot going on between 'Carter' and 'O'Neill' under the surface. They manage to keep the lid on, but often just barely. The episode 'Solitudes' in season 1 had some of the best drama ever seen on television. The love between the two made the prospect of dying bearable because they faced it together.
'Carter' and 'Jackson' often have to smooth over some of the turbulence created by 'O'Neill'. Yet 'O'Neill's' tactical instincts always seem sound. He understands what to do without having to think about the matter. The team has several times been placed in jeopardy by the others not listening to his orders.
The quality declined markedly in seasons 9 and 10. The original story arc was mostly used up and the new villains never really caught my interest. Ben Browder was far inferior to RDA in carrying the show. He had his rare moments with Claudia Black, but that was all. Amanda Tapping was phoning in her performances these two seasons. You could see her greatly changed appearance after having a baby. She was probably thinking more about the child than the show.
The spin-off 'Stargate Atlantis' has a few moments, but is mostly a weaker effort. The major characters lack the chemistry of the cast of the original. The villains (Wraiths) are so improbable as to be ludicrous. Maybe Amanda Tapping can breathe some life into the program or it won't last beyond the fourth season.
There has always been a problem for me in the special effects for the show. To have spaceships shaped as pyramids is a design monstrosity seldom equaled in Sci-Fi. The use of torches for illumination in these ships is just as bad. The campy use of decor from ancient Egypt concealing ultra-modern technology is just as hard to accept.
I wondered about some of the continuity on the show too. In the season 2 opener, 'Daniel Jackson' is shot up and his uniform has a gaping hole where he was wounded. He crawls into a sarcophagus and it heals his body and restores his uniform like it just came off the rack in the wardrobe closet. The episode 'Hathor' has a sarcophagus fall into the hands of the SGC, yet it is never mentioned again. This device could have been used in several later episodes on 'Daniel', 'O'Neill', and 'Dr. Frasier'.