The story so far: One of my local TV stations used to run The Simpsons syndicated when I got home and was eating dinner. When Chuck started it was right after The Simpsons so even though the premise wasn't that promising I ended up watching maybe a third or so of the first season. Eventually The Simpsons was ditched in favor of Jeopardy or some other mindless game show so I now almost never watch "live" TV and consequently was mostly going to pass on Chuck )even though that makes it sound like I thought this through to a decision when really I never considered it). But a guy at work kept talking it up and eventually I watched nearly all the second season, missing only a few at the first. And it was pretty fun in a mostly haphazard sort of way. There was a big mis-step when they decided to Get Serious and have Chuck secretly witness Sarah murder an unarmed spy who was threatening him but I knew the show couldn't pull off any real drama and sure enough that lasted barely into the next episode. Then there was a big, reasonably inventive storyline at the end (Chevy Chase as an evil mastermind!) that worked pretty well and made big shakeups in the premise.
The story today: Except Season Three undid everything in the first episode. The worst decision was to kill off the corporate-shill store manager but not reveal that to most of the characters, instead telling them he'd been transferred to another store. So why not just transfer him? The murder is out of keeping with the show's tone, especially when it went to this much trouble to reboot. That was the other mistake - undoing the previous story elements so that the status quo is the same as the first two seasons.
There is one change that's been kept so far which is that Chuck now has an improved Intersect in his head that will let him do actions he couldn't before - kung fu, surgical procedures, speak foreign languages, etc. The mistake is that the writers decided to make it defective so that sometimes the Intersect works and sometimes not. Stated that way this seems like a decent approach that avoids making Chuck a superspy but clearly it wasn't thought completely through. The problem is that the defect is being used so that the Intersect doesn't work when that's "dramatic" but works when the writers need it to. So in a recent episode Chuck learned a martial arts kick when it was useful for a comic gag (and to start a subplot) but not when it was actually needed for a real fight.
There also doesn't seem to have been much thought about how the show should actually work now that the original concept has been more or less played out. The conflict between spy activity and Buy More regular life drove most of the humor but now that connection is long gone and we're left with a decent workplace sitcom and a half-assed spy show. Getting the two together will start to be more and more arbitrary, possibly ending up with the approach taken by Friends where all the main characters had to be in every episode so eventually the two or three main stories had no relation to each other and could have been shuffled with no effect on each other.
Oh and that whole romantic/sexual tension stuff is just not tense or funny or interesting - same for Chuck's timid nerdiness. I may give the show one more episode to do something but most likely it's a finished deal.