- The way they acted around the transporter. The Enterprise was equipped with one, but due to the fact that it was brand new, it was rarely used. I like the weariness, it would have been absurd to have them just use it as easily as characters in the other Trek series.
- The setting. I know a lot of Trekkies abhorred the idea of a show taking place before The Original Series and I was one of them. I got over it though. The concept of chronicling the pre-Federation days of the Trekverse and how the Federation eventually formed was interesting.
- The aliens. It was nice to see recurring appearances by races like the Andorians and Tellarites. It was always odd that despite them being two of the founding members of the Federation, you only saw the Tellarites once (The Journey to Babel) and the Andorians like three times (The Journey to Babel, Star Trek IV: The Voyage Home, The Offspring) prior to Enterprise.
- Their in-universe explanation for the two different types of Klingons. Talk about solving the second biggest mystery of Star Trek (the biggest being how Kirk managed to avoid getting space herpes from all the alien chicks he banged). If you've never watched Enterprise, the explanation was that the Klingons were experimenting with the DNA from augmented humans created by Arik Soong, the direct descendant of Noonian Soong, the creator of Data, Lor, and B4. Their goal was just to improve their species, but things got out of control and the smooth-foreheaded Klingons seen in TOS were the result.
- The Enterprise itself. Here, this will help:
It's obvious that Enterprise was used for the show's title because it's an instantly recognizable name in Star Trek. I think they should have used a different name, however. Odyssey would have been a good one, along with Pathfinder and some others.
- The weapons, oh god, the weapons. Phase cannons/pistols? Spatial and photonic torpedoes? Sweet Zombie Jesus! Here's the problem, it was established in Balance of Terror that the Earth-Romulan War was fought with lasers and primitive atomic weapons. We're supposed to believe that they went from phase cannons and photonic torpedoes to lasers and nukes? Another TOS episode, The Cage, also shows that Starfleet was using lasers during Christopher Pike's time as Captain of the Enterprise. No, whoever came up with phase weapons either wasn't aware of the lasers and nukes thing or chose to retcon it very lazily. All they did was take the word phaser and dropped the 'r' off the end, then added an 'ic' to the end of photon.
- The Xindi and Alien Nazi story arcs were just horrible. Nuff said.
- All the needless sex and brief nudity. Hoshi Sato appears nude in the first episode (we don't see anything) and T'Pol has a few nude scenes herself (ditto). Then there's all the scenes where characters are in that decontamination room, rubbing each other down. I don't mind a bit of sex in my Trek, but it was obvious that the writers or producers did it to appeal to a base and all they succeeded in doing was cheapening the show and the characters.
Pictures via Agony Booth and Memory Alpha.