I love this kind of set-up. No hanging storylines, just pure story. It ranges from totally silly to truly excellent, and it is very refreshing (I'm watching these on DVD).
However, from my position of too-educated person in the 21st century, I have noticed a troubling element. Why do all these people need some educated (Sam speaks five languages and has seven degrees or vice versa, I can't remember which), white male to fix their problems for them? What, they aren't capable of doing it themselves? Hello, white man's burden.
And I've determined that the reason it works at all is because of Scott Bakula. He's definitely a TV actor. I don’t expect to ever see him on the silver screen (and these days, why would he need to be?). But as a TV actor, he's quite respectable. As Quantum Leap's Sam he has two things going for him: he comes off as truly kind. And two, the man has no self-consciousness.
I've mentioned before that Tony Shalhoub has this quality. You can usually spot actors who do; that is, actors who are so little concerned with their own egos, they just float inside a part. (Robin Williams, who is a fine actor, is not a good example. Tom Hanks is, most of the time.)
In several Quantum Leap episodes, Sam "jumps" into a woman's body (and believe me, there's no way I could have written that sentence without it sounding vaguely salacious). The first time, a lot of the script is centered on Sam trying to wear heels, Sam dressing in 1960s mini skirts. In the second, he "jumps" into a 1980s mom in Texas and spends the entire episode running around in a long jean skirt with a large buckle belt. And here's where Scott Bakula excels: he does both absolutely naturally. In a way, the two approaches are American drag versus British drag. With the former, the emphasis is always on the clothes and the outrageous garb accompanied by the deep voice. British drag, on the other hand, can be found in pantomimes (where the men play the older women's parts: think Charley's Aunt); the sex role switcheroo isn't the emphasis per se, although it is part of the humor. Bakula, in woman's garb, can play off both forms of drag with very little effort and without losing his masculinity (which is necessary to other episodes where he plays the hero-gets-the-bad-guy-gets-the-girl). And consequently, Quantum Leap works. (Even Al grows on you after awhile.)