I first saw TPM some ten days after the Croatian première (which was almost five months after the domestic release, that kind of shit was normal back in the nineties), and I don't remember a single person leaving the (completely packed) theatre bitching about the movie. In fact, a lot of people appeared totally psyched (mostly because of the visuals, I reckon). Also, out of the dozens of my friends and schoolmates who saw it (it was considered a "must see", much like Avatar a decade later), not one of them talked trash about it.
You raise an excellent point. When TPM was first released, it seemed as if everyone loved it. It wasn't until about 3-4 months later that the honeymoon period was over when opinion turned.