Tall jeans used to mean one extra inseam length tacked onto the end of a size run, usually in one wash, usually gone by February. That has changed properly in the last few years. There is more choice in cut now, not just length, so someone who is five foot ten doesn't have to choose between a straight leg that ends at the ankle bone in a slightly accusing way or a bootcut from 2004. It is better, though the good ones still sell out in the only size that matters within about a fortnight, so the system is improved rather than solved.
Where these earn their place is in anything that needs the leg line to run uninterrupted, which is most things. A long straight or wide leg tall jean works for daytime in fairly much any season, under a coat in winter without pooling at the ankle, with a sandal in summer without stopping three inches too soon. What tells you a pair is well made is mostly in your hands before you've even tried them on. Hold the leg up and look at the hem, a proper one is finished flat with no puckering, not just overlocked and left. Check the rise at the back, cheap tall jeans often just add length to the leg and forget the body needs more room too, so you get a long leg stuck onto a rise that fits like it was drawn for someone shorter. The denim itself should have a bit of weight to it, not that thin, slightly see through stretch that goes baggy at the knee by lunchtime. Rivets and the button should feel properly set, not sitting slightly proud like they might pop given the chance.
They do less well with anything already long in proportion up top, a maxi cardigan or a long blazer worn open, because then you've got length fighting length and the whole outfit reads as one tall rectangle with a face at the top. Balance it with something that stops at the hip or the high thigh instead. And a wide leg tall jean is the wrong call entirely if you're after something for cycling, a long commute on public transport, or a day where the hem is going to drag through anything wet, because that extra length that looks so good standing still becomes a liability the second you're moving properly.
Wash them inside out and on a cool cycle, it keeps the colour and the hem stitching intact for far longer than the label's actual instructions suggest.