Definitely one of the funnest, funniest shows ever. It's Captain Awesome. Once you buy into the premise the mix of comedy, action, drama and romance are super enjoyable - just a fun joyous mix. It was a cult classic when it was on network TV and I was in the cult and caught most of the first 4 seasons when they aired, but when they switched the final season to Friday nights we weren't home in time to watch it much, didn't have a DVR at the time, and hence didn't see more than an episode or two.
Not sure whether this show ever streamed on Netflix (we went a few years without Netflix). It finally appeared on Prime a few months back and we started watching again from the first season, since it had been more than a decade since we'd seen those episodes. What with alternating between this and other shows, plus live sports and stuff on live TV we wanted to watch, it took some time to work all the way through to the final episode. I'm glad I finally made it through and if there is a Chuck cult I'm still a member in good standing.
Maybe the show only appeals to a certain kind of person, but it always boggled my mind that this show never found a wider audience. Seasons 1-3 are the strongest but the 4th and 5th seasons are also worth watching more than 90% of what is on TV, and that includes acclaimed HBO series and such. Would love to see a straight to streaming reboot - other cult classic shows (Arrested Development, The Mindy Project, The Expanse to name three) have survived that way and I don't see why the same model couldn't work for this show.