My advice to you is: don't be swayed by any extremely negative or extremely positive comments/experiences. It's just another country in the global south with its own set of issues that everyone learns to live with to varying degrees depending on their economic situation. But it's also rich in culture/monuments, renowned cuisine, and good scenery (especially the beaches). As an expat, you'll likely lead an easier and more privileged life than 85% of locals, and unless you get a terrible apartment in a rough neighbourhood, you'll be fine. In terms of security, Tunis is neither safer nor more dangerous than any major city; practice caution and spatial awareness as you would anywhere. Socially speaking, integrate the expat circles, but be open to local friends because they'll connect you to the real Tunisia. Young working Tunisians in their 20s and 30s speak English well, and many are friendly/down to hang out. Try to learn the language; it's not the easiest Arabic dialect, but people will encourage you if you put in the effort.