It's pretty awful. I've spent time in Will and Dupage county in Illinois (3 months each) and I can say that I never want to go back. 95% of the people locked up are there because of drugs or drug related crimes. Even if they're there for a burglary, larceny, or whatever - it's because of an underlying drug problem, mental health issue, or a wonderful combination of both. I very rarely met anyone inside who has lived a sober or easy life.
Everything is structured. The time you have out to eat, the time you can sleep, the time you have towards luxury, etc. Very little (if anything) is left up to the inmates to decide because it usually causes conflict. Ever argue with someone about the TV channel? Try arguing with 40+ pissed off and nervous guys about the TV and you see why the state wants to decide what everyone does and how they do it.
Food is awful. It's about 10x worse than a frozen dinner and will absolutely make anyone immediately reflex gag the first time they try to eat it. Ask almost anyone who has been locked up and they'll tell you - they ate that shit because they were starving, not because they had to.
Recreation is essentially the same shit every day. Play spades, poker, read, watch TV, or talk on the phone. I spent most of my time reading books, drinking coffee and socializing/making friends with everyone I could. I learned that my education and outside ties to information (TV schedule, 3rd party calls, etc) were a great thing to have and definitely helped me be at the top of pod when it came to people everyone wants to know.
If you're broke in jail, you're nearly fucked. Imagine going on vacation without a fucking dollar to your name. It's like that, except about 10x worse. You cannot survive on state food and soap alone. You need to have some extras in jail because what the state gives you just isn't enough. This is why Keefe (commissary company) is a massive, probably multi billion dollar business at this point because they sell individual packets of Ramen noodles for $1 a piece and people eat that shit up every week. I was buying 10 a week for currency and just to survive on every night because what they fed us at chow just wasn't enough to life off of. Imagine being starving and watching everyone else dip in to their boxes for "outside" food. Yeah. It sucks.
Finally, I'll dig in to the social aspect of jail. If you've got social problems or anxiety or whatever - you're gonna have a very bad time. You are never alone and have to shit, shower, sleep, and whatever else in front of a bunch of other dudes. You need to have a sense of humor and the ability to make friends in jail. It's an asset to have jail buddies, it's a liability if you don't. People love to talk in jail and you are at a serious disadvantage if you don't have even a shred of social skills. People can smell the fear/newbie in guys who are fresh on the deck and they get preyed upon or "got over" on for their commissary or whatever all the time. If it looks like you're going to be a fucking mark (weak person) then you're going to get shit on. A lot. And there isn't much you can do about it, either.
Overall though if you know how to socialize and you're not an idiot - you'll be fine in jail and you'll learn a lot about yourself and how you deal with conflict. Everything is a conflict in jail. The line for the shower, phones, chow, etc. It's how you handle it that defines you as a person. Once you survive jail, you feel a sense of inner strength because jail does break a lot of people and during your stay, you will see how it breaks people down and how people 'tick' at their most basic level without being in society.
My big problem now is that I have nothing to do once I'm out. I'm literally stuck with my dick in my hand and I'm nearly unemployable due to my record. I didn't rape any kids or anything but I've got theft on my records which automatically eliminates me from a large portion of menial jobs out there. It sucks. It's a permanent reminder of a temporarily problem I had a few years ago and it never seems to go away. I probably needed to be in jail for what I did but I shouldn't have to live with the burden for the rest of my life, especially if I'm trying to turn shit around and be a productive member of society. There are very, very few opportunities for ex cons in todays world which is why recidivism is so high. I used to call "BULLSHIT!" to people who would talk about how it's not easy to get back on the horse after going to jail or prison but now that I've personally experienced it, I can completely relate. It's depressing and definitely casts a large shadow over everything in my life.
Anyway, enjoy. I'm removing this post in a few hours so hopefully you'll see it.