There's a huge difference between passable and horrible. Generally, the smaller school/classes the better, but certain people, especially teachers, can ruin the whole experience.
Regarding the friends thing and not wanting to be a shut-in, just don't make school your only place to meet people.
For comparison, I recently graduated after having commuted about an hour extra each way to go to a private (but publicly funded) HS. A few really good teachers, but I probably wouldn't do it again (at that school) thanks to the specialization-relevant teachers generally being quite horrible, as well as some disagreements with school management (for example, they tried to force students to collect money for a pretty questionable charity to generate PR for the school, threatening to pull CSN money if you refused).