A sweatshirt suits almost anyone who wants something that looks pulled together without trying very hard, which is most of us on most days. It's at its best on women who like a bit of structure through the body rather than something that hangs loose and shapeless, and it works brilliantly as a layering piece if you want more coverage without reaching for yet another vest underneath. If you run warm, or you hate anything sitting close to the neck, I'd think twice, because a lot of sweatshirts are cut generously through the chest and can feel like wearing a small duvet by midafternoon.
Colour wise, I've had the most mileage out of soft greys, deep navy and a proper bottle green, because they don't show every crumb or coffee drip the way pale pink or cream does within the hour. A heathered grey is especially forgiving, it hides lint and bobbling better than a flat colour ever will, so if you're buying one to actually live in rather than photograph, run your hand across the fabric in the shop and check it doesn't feel thin enough to pill by October. Black is lovely but shows every wash mark and dog hair going, so I only buy it if I know I'll wash it on a gentle cycle and mean it.
A good sweatshirt earns its keep from early autumn right through to the coldest part of winter, under a coat on the school run, over a long sleeve top on a weekend where you're in and out of the car all day, or thrown on with a skirt for something that needs to look slightly more deliberate than a hoodie but still feels like loungewear underneath. I'd check the sleeve comes properly to the wrist and the hem sits low enough that it doesn't ride up when you lift your arms, because a sweatshirt that creeps up at the waist defeats the whole point of wearing something cosy in the first place.
Where it falls apart is pairing it with anything else bulky, a padded coat over a thick sweatshirt turns you into a shape with no waist at all, and it sits oddly with anything delicate or tailored, a sweatshirt over a silky midi skirt just looks like you got dressed in the dark. The detail that makes a good one worth keeping is a hem with proper ribbing that holds its shape wash after wash, rather than one that goes slack and starts looking like a sad elastic band by February.