Stargate Universe - It did get very good in the second half of Season 2. However, for me, S1 was a bit of a slog to get through most of the time. Almost none of the characters had anything to enthuse me about. I disliked watching almost all of them. I'm not just talkling about characters that are morally repugnant, I mean characters that I really had no interest in, that I wished would just disappear. This does change over time though, and by the end of S2, I was very sorry to see it had been cancelled, because there were quite a few of the characters that I did want to know more about (Despite wanting many of them spaced in S1). SG-1 being watched first, adds to the mythology for Stargate Universe (SGU), but, not necessarily necessary. Stargate Atlantis (SGA), doesn't really have any impact on SGU.
SG-1, IMHO, is good, solid Military SciFi Action, with some very funny one liners and some terrific guest stars. When I first watched it, I started in the middle on SyFy channel reruns (They used to marathon 4 episodes every Monday) and missed some nights (Mean I missed 4 episodes in a row if I only missed 1 week) and my opinion was, there were hardly any episodes lower than a 6 out of 10, but, also very 9out of 10 or better. Watching it all in order from the beginning at my own pace (I too often consume a whole season in a week or less after work, since I rarely watch regular TV and always having DVDs in the background while I do other things) I found there were actually quite a few 9 and 10 episodes afterall, but, still feel it's rare for an episode to drop below a 6 or 7 out of 10.
SGA - is a direct spinoff of SG-1. While you don't need
to watch SG-1 first, it enhances your enjoyment of it, IMHO.