The interior: Comfortable cloth seats, fairly plain in general. The front seats have decent space, but the back seats are really tight. I think that having an infant seat in the back would mean that the front passenger would be eating knee sandwiches. The hatch space also looked very small to me, and I had doubts about my dog getting in there comfortably.
Driving: Great clutch feel, and shifting was a delight. Easy to shift without being so easy that you feel like you're giving up the fun of driving stick. Good handling, plenty of power and torque (270 hp, 252 lb-ft) of torque.
The tech: Backup cam. Bluetooth? Maybe? Honestly, I was so focused on trying to find something fun. That I didn't play with the infotainment at all.
Value: Unsure. Fuel economy is rated at 22-30 mpg, with premium recommended (91 minimum, 93 where I am, since we don't have 91). It had 37k miles on it, listed at $17k dollars. That seems like a pretty decent deal to me, but I'm willing to bet that many (not all) Focus ST owners probably drive their cars pretty hard. If it's 37k miles of hard driving, I'd be concerned about longevity / maintenance.
This is another car with one-foot in the grave in the US, as Ford decided not to bring them back to the US after 2018. There are a decent number of used ones out there, but I'd definitely recommend a PPI (pre-purchase inspection), to see just how hard they've been driven.
If you don't need the space, you can check out it's little brother, the Fiesta ST, which I've heard nothing but good things about. And if you want all-wheel drive, more power, and have some extra cash to spend, check out the Focus RS. For a daily driver, I think the Focus ST is a pretty good sweet-spot though.