Though it's probably 15 years since I've even seen it (and I've never seen the live action movie), I have a soft spot for Inspector Gadget. To appreciate how this can be, I think you have to be old enough to remember what a wasteland western TV cartoon programming had become by the mid 80's.
In fact it had been pretty wretched since the 60's, but my generation, and to a lesser extent the generation before mine, weren't old enough to know any better. We'd been raised on a Saturday morning diet of increasingly weak Hanna Barbera and Filmation shows. These two studios still dominated TV cartoons in the early 80's. To give you an idea of how bad things were, in the year or so before 'Inspector Gadget', Filmation treated us to such memorable series as the animated versions of 'Gilligan's Island', and 'Laverne and Shirley in the Army', while Hanna Barbera produced such treats as the animated version of 'Mork and Mindy'. By the early to mid 80's , partly due to the Reagan administration's relaxation of laws about what constituted educational content, TV cartoons were largely swamped with 30 minute toy advertisents like 'Rainbow Bright', 'Pound Puppies', 'G.I. Joe', et al.
With one or two honourable exceptions, the only really watchable stuff (for a teenager anyway) was coming out of France and Japan (Mysterious Cities of Gold, Spartakus and the Sun Beneath the Sea, Robotech (even though that was guilty of being part of the merchandising boom, at least it was a cartoon first), etc).
So I suppose it was no surprise that when a show came along that was actually original, funny, not trying to sell you a transforming robot, and had decent production values, it turned out to be from outside of the US again (well, technically Gadget was French/Canadian/American with a bit of Japanese thrown in, but it sure wasn't Hanna Barbara anyway).
The show might look a bit old-fashioned and unremarkable by today's standards, but in the dim days before the new animation dawn ushered in by 'Who Framed Roger Rabbit', it was one of the few rays of light in children's TV cartoons - to the extent that even at age 20 or thereabouts, I could dig it. Of course back then it wasn't yet cool for adults to like cartoons, but I used to play in a band, and taught myself the theme music to 'Inspector Gadget' and would sometimes play it between sets, and people used to love it, so don't tell me there weren't closet cartoon fans out there.
Anyway, that's one of my customary essays out of the way. What about the show? Well it suffered from a few pre-90's cliches. The moralistic endings, and the lack of any content really aimed at adults, but the production quality was better than the limited animation that filmation and HB had been getting away with forever. Secondly, the choice of Don Adams in the lead voice role was utterly brilliant and a real coup, as Gadget was essentially a cross between Adam's old 'Get Smart' persona, and Inspector Clouseau (The Pink Panther). A nice French-american crossover.
The plots were repetitive and predictable, with various set pieces such as Gadget's always blowing up Inspector Quimby, and always mistaking Brain for a M.A.D. agent, but this was ok. A lot of the fun and variation came from the Penny/Brain action behind the scenes, and the slapstick situations Gadget would get into with his malfunctioning contraptions. Penny's 'computer book' was also a a rather clever anticipation of the laptop computer, too (remembering that when this film came out, the Commodore 64 was the bee's knees). Penny herself could be slightly irritating at times, but not so much that it spoiled the show. Brain was fun, and I used to have a figurine on the dashboard of my car. I was really upset when I sold the car, some guy woke me up at 6 AM when I couldn't even think, stuffed some money in my hand and drove off with Brain still in the car (a friend got me a new one)
It's not my favourite cartoon of the 80's, but it's a damn sight better than most other stuff on english speaking TV from that era.