As was the case with Aerith, I have no knowledge of Tifa - well, not quite true, she was in the movie (as was Aerith briefly), but all I learned from that is that she's got a nice voice, looks good in black, and fights like the wrath of god when she's angry. I've never played the game, so miniskirt Tifa is new to me, bought on a whim due to good looks and the Yuffie action figure being very technically impressive.
She's not quite that good, but she's far from poor. Let's do the good stuff first: she looks great, with a very characterful sculpt that's virtually unmarred by articulation, good colours, and sufficient mobility to strike a striking pose. Her visual design is anime-styled (or manga, I never remember which came first), most noticeably her elfin face with the pointed chin and biiiiig eyes - so far as these things go it's good work, and quite attractive in a cute kind of way, but if it's realism you're looking for you won't really find it. She also has rather prodigious breasts, which - well, unless there's some kind of scaffold-like bra under that top they're not behaving realistically, but there's some sculpted folds in the fabric that at least makes an effort at looking credible - if you did stick a couple of helium balloons under a tight tank top, that's what it'd look like. Her colour pallete is admirably restrained, with her skin a rather muted cream/yellow, and the only real stand-out colours her sombre red boots and gloves. Apropos of nothing, I particularly like the paintwork on her gloves, the appearance is just right for a stocking-like gauzy fabric - why she'd be wearing anything like that (along with a big metal elbow pad) I have no idea, but it looks good.
She also has really nice hair, with the black fading out to transparent dark red at the tips - again it's not the most real-looking effect, but it does look good. You won't see it mostly, since it's behind her back, but she has the 'dolphin tail' hairdo that's apparently her trademark.
The down side of her is twofold: firstly, she has no accessories besides a stand and an alternate pair of hands. That may seem a minor matter, and true it's not the end of the world, but having no weapons or toys to wield leaves her with just her own body to strike a pose with, and good as it is, there are areas where the manufacturers have sacrificed a bit of poseability for looks. Her elbows, for instance, only just reach a ninety degree turn, which rules out some postures. And this ties to the second problem with her: those braces. They're a rubbery plastic, so you can turn her torso joint and they'll stretch to match, but they're not very elastic, and won't un-stretch very much. Basically, play around with her torso joint too much, and she'll wind up with braces that are too long, bowing out to either side instead of attaching tightly. You can see what I mean in the photo - and bear in mind, that's with a minimal amount of posing, not a lot more than it took for me to find a good pose for her and leave her in it. If you play with this figure, or re-pose it more than a couple of times, those braces will be irreparably damaged. That, of course, also limits how well she can be posed generally, because it's tricky to find a good pose without trying a whole bunch of options.
Having said all that, she's still a very good figure - not as good as Aerith or Advent Children Yuffie, but if you're a Tifa fan from the game you definitely want this. The stand is the usual Final Fantasy flying clasp, so she can be posed in mid-leap or flying kick or whatever it is she does up in the air, and the alternate hands have their fingers splayed, in a ready-to-fight kind of way. Even with the drawbacks to her torso, she's exceptionally mobile, with a neck ball joint, ball joint shoulders mounted on a hunch/stretch peg joint, peg elbows, swivel wrists, a torso ball, hip ball joints, peg knees, swivel ankles, and mid-foot pegs to keep her soles flat on the ground. Be careful with her braces, and she'll do you proud.