I've been obsessed with sweater coats lately and their multitude of pluses and minuses. Sweater coats can be tricky to pick out, however. A bad one can make you feel as though you're wearing something that's one step up from a bathrobe out in public. Unlike wool coats or trenches, they don't have a lot of built-in structure and really cling to your body. That means if you have any lumps and bumps in your outfits (say, a wide belt cinched over your ensemble or pocket flaps on your trousers), the sweater coat will cling to that and make you look as though it's your body, not what's on it, that's lumpy and bumpy. 3/4-length versions are especially tricky for this reason. Plus, sweater knits have a tendency to pill easily and might require more care to look good for a long time to come (sweater shaver anyone?).
On the other hand, the right one can give an ordinary tee-and-jeans combo or a skirt and tights a cozy look for fall. This is especially true if the sweater coat has neat details like oversized buttons and a belted waist. I also prefer a chunky texture and neat patterns in the knit like cables and popcorn-like ruching or crochet-like details. As for length, I think a car coat length that hits just below the hip is ideal: it's long enough to highlight an hourglass figure and keep you warm, but not so long that the bottom looks shapeless and the sweater coat seems as though it's just hanging on your frame.
These are some of my favourite picks from the Internet scoping I've done so far. Enjoy!
Alice & Olivia cardigan, Bluefly, $189
Autumn Cashmere cardigan, Bluefly, $239
Sweater coat, Gap, $68
Long belted cardigan, Topshop, 40 pounds