All Trek has continuity problems, as King Daniel points out. Enterprise's are no worse than those of any prior series or movie. It's just that it covers a period that we had decades to build up assumptions and expectations about. Most of the things that people saw as "continuity errors" in ENT were really contradictions of their preconceptions and beliefs about the 22nd century, rather than any actual canonical information.
Really, it would've been a total waste if all ENT had done was confirm our existing assumptions about the era. That would've been boring and pointless. It's good to be surprised.
But that was the problem. ENT, stylistically, structurally, and writing-wise, really wasn't all that different from Voyager which came before it.
I have no problems with changing preconceptions, but for the first two years the show was simply about a crew on a ship visiting planets/aliens-of-the-week. They even had a Seven-of-Nine clone. Every script for the first two seasons could have easily been written for Voyager.
It wasn't that my preconceptions of the 22nd century had changed, it was that I was basically being shown that Star Trek's past wasn't all that different from Star Trek's future. Stylistically and structurally, Forbidden Planet
was a better Star Trek prequel than ENT was.