What people mean by having finasteride maintain their hair is that the 'balding clock' has basically been stopped to where it was before they got on the medication, thus while on finasteride, they won't progress going further bald from where they were pre-medication.
Does that mean propecia can give u slight regrowth and then maintain or when they say maintain people mean that they have not fallen below baseline throughout the time they have used finasteride?
Both. I would say that being on finasteride alone, most people maintain or get very modest regrowth, with a few getting better regrowth and some slowly slipping below baseline. In general I'd say that it depends on how aggressive one's balding is, how fast one acted on it and then the luck of the draw with the medication. But generally speaking, from what I've seen, the majority of people seem to maintain on finasteride alone. The faster it is acted on, the better.
I didn't regrow much at all on finasteride alone in 9 months (though I'll still continue taking it of course, I believe it's essential), just had slightly better hair texture and the already thick-ish areas got further thickened up, while the very thin areas stayed as they were, or improved very little, which ironically enough made my Norwood 3½ Vertex look even worse with the contrast between the thick/thin spots. I wasted 4 years before I got on finasteride, though, if I had acted faster, maybe I would have been better on finasteride only. (I did get a ton of regrowth on minoxidil though, which I added into my regimen later).