To be honest, that's what completely shat me about the series from time to time. They'd come up with a great story or twist and give you the impression it would stick, only to hit the reset button at the end or the episode (or by part 2). I got dragged to this by my fiancée but really enjoyed it . But it was a lot of little changes that did it for me, things like ships meeting and NOT finding themselves meeting on the same level like on a 2D plane (plain?) (that always bugged me! B5 spcae was 3D! ), tiny things like the Fed ships having CIWS (look carefully during the first and last fights), swearing and fisticuffs. I could go on...
...and I will. The swearing and attitudes the characters had was an important step, I thought. For me, I always thought the characters in the Next Gen Movies/series' were too inoffensive and sugar coated. I'd watch how they'd react to an event and it always seemed they their responses were a little fake or manicured. Look at the way they deal with the Borg in the Series. It's supposed to be the 'ultimate' fear they've faced, but they're hardly breaking a sweat, no one loses control, no one freaks out, no one's trying to make peace, etc.
That's why I dug this. The fighting, the smartarsed-ness, the quips and taunts all made it feel edgier and more realistic (behaviourally) to me. It's worth seeing for sure, but if you figure the storyline of TOS/TMP is akin to a sacred script, you'll be bugged.