I'm not an astrophysicist, but I know a few.
1. I'm not sure what exactly you mean here. They're not all that different from anyone else. Going through graduate school is a demanding experience and generally requires you to put in more time than for a full-time job. You then move into post-doctoral work and finally into academia. Most of the successful people in this field are very driven, and thus they spend "free time" also working on their research. But you're not locked in a basement somewhere. You do have spare time.
2. As far as social life goes, it's a little different than having a regular 9-5 job. It can be hard, for example, to talk about work outside of work (ie. with your spouse), simply because the average person won't understand what you do without you first delving into an extended explanation.
3. Doing research professionally is not a 9-5 job, in general. Theorists have a little more opportunity to set their own hours. But in astronomy for example, you have to book time on different telescopes and make use of it when you have it. So you can expect lots of late nights staring at the stars.
4. Most academic work is done in universities. You can always branch out into the industrial world, but then you're likely doing research to advance a particular product or service as opposed to advancing the field in general.
5. You won't make a lot of money in academia. During life as a graduate student, you're barely making enough to cover tuition, rent and groceries. Post-doctoral work pays a little more. Ballpark: $30-40k/year. But you're moving from contract to contract working for ~2 years at a time and usually without great benefits. By the time you enter tenure-track positions, the pay gets better. Starting ballpark ~$50k/year and then going up from there. In some institutions, full professors make the "six figure" salary, but I'm not sure that's the norm. You might want to check out:
http://www.aip.org/statistics/
for some solid numbers.
6. Strictly speaking academia, it can be very competative. As I mentioned, following the PhD, you jump from post-doc to post-doc, which are often in different cities. So laying down some roots can be difficult, and it can be demanding on a family. That being said, with a PhD in physics you can do quite well for yourself in the "real world" provided you know how to market your skills.
