The first two seasons of TNG were pretty bad, but after that they improved. The big issue they overcame was breaking away from the original series mold.
In the early episodes you can really see how they tried to take original series roles and divide them up among a new crew (Riker as the stand-in womanizer for Kirk, Data as the stand-in for Spock, etc.). It also uses a LOT of the conventions of the old show trying to get ahold of that remnant original series audience. We can look back on the omnipotent Q abducting people and making them fight dog-faced Napoleonic soldiers and cringe at how hokey it is. We can look back on the relatively-omnipotent Excalbians abducting people and making them fight Kahless and Genghis Khan with a little help from Abraham Lincoln and get a giddy little thrill. The difference is that TOS had a shoestring budget was aimed at a more forgiving youth audience, and TNG had a respectable budget (but still hokey scripts) and was aimed at those same people after they grew up in to sophisticated adults.
It took two seasons, but they eventually got over that hurdle and turned into their own show. When asked when he first knew that they "had something" in the show, Patrick Stewart said it was while shooting "the Measure of a Man" (s2, ep9). If you think of the question a different way -- "at what point did you realize the job wasn't necessarily shit?" -- then the answer says a lot about the quality of the preceding 33 episodes.