People saw it, and weren't impressed with what they saw.
I think that's probably a fair assessment.
is a good episode in many ways, but a flawed pilot imo because so much time is spent with Sisko in this otherworldy state with the Prophets, which, while interesting in a "high concept" sort of way, is pretty slow and dull.
Past the pilot, DS9 was, as I recall, often using stories pitched to TNG, but that TNG didn't use, so basically cast-off ideas for a significant number of episodes.
The idea of a space station on the frontier is good, but it took a while for the writers to really find a direction. In the meantime, season one feels too much like a more static, less glitzy, less exciting version of TNG.
The show has a good cast, and I think the non-Starfleet characters were a strong point from early on (Kira, Odo, Quark), along with O'Brien among the Starfleet cast. He's always been well-liked. But none of the Starfleet characters really stood out compared to characters like Picard and Data.
There are reasons to like the show from early on, and to prefer it to TNG, but these aspects of the show have more of a "niche" sort of appeal: more flawed characters, a less idyllic setting, some political and religious ideas being addressed, etc.
It was a different time as well. Early TNG, for example, is pretty awful. Early DS9 actually compares favorably to it (though that perhaps isn't saying much). But, back then, it was the first opportunity people had had to watch new Trek episodes on television since TOS. By the time DS9 aired, people were used to a much more polished product, and many of the TNG characters had already become revered by fans (in a way that they weren't necessarily, when TNG first aired).