Enterprise was a little flawed from the get go. It was meant to be a prequel set a century before Kirk, but the kept all the same technology that Kirk and Picard had and instead of a meaningful "birth of the Federation" storyline we got the same disposable and forgettable planet-of-the-week plots which we'd seen ad nausium in TOS, TNG and VOY.
They originally dropped "Star Trek" from the title because they wanted to attract a wider audience - I guess the rationale being "If it says 'Star Trek' in the title it's just for Trekkies" (*cut to J.J. Abrams' laughing*)
Archer was annoying, incredibly naive (we're talking common sense fails here, not believable first-timers-in-space mistakes) and foolish, pestering aliens like an intergalactic Jehovah's Witness.
BUT, in spite of all this they managed a few great episodes in the first two seasons (as well as lots of cack or completely forgettable ones). And around the time of "Regeneration" I thought the show was starting to hit it's stride. Then came the season three revamp and Xindi story. Archer was fixed (and changed so much, he came across as bipolar), the others stopped being cardboard cutouts and for the first time, I was eagerly awaiting next week's episode because I didn't have a clue what was going to happen next. It was fun! My favourite season in all of Trek.
In season four they became the prequel that people expected from the get-go. I liked it, although not as much as the Xindi story.
Last year I rewatched all of The Original Series, Enterprise and Voyager, and enjoyed them. This year I tried to rewatch The Next Generation and couldn't. I loved it at the time, but it's aged terribly
. Bad acting and direction, trite morals, little to no action....ugh.