We are asked this question quite a lot, as this author did indeed used to live and work there. The short answer is that it is very bad. However the good news is that it doesn't really get better or worse; it's always just very bad indeed. Cairo never changes.
Arrival
Although Cairo International Airport pretends to have gotten better in previous years, do not believe this. It has just changed in awfulness.
In the old days you would have to run from the plane in abominable heat to a set of strange desks that would sell you a visa stamp before hordes of other people got in front of you and caused you to wait for hours in the sweltering heat. This has now become more civilised (although the procedure is essentially the same).
However the relative smoothness of the procedure has been decompensated by the fact that once you enter the 'arrivals hall' - a giant atrium full of bodies with very little air conditioning - the exercise of actually getting out of the door into the open air can take you one to two hours because thousands of people are cramming to get out of the same tiny door. And then there is a giant car park full of vehicles one of
which will be the taxi you are destined to take. Irrespective of what overprice you pay, the journey will be the same: two hours plus into the centre of the city in bumper-to-bumper smog-thick noisy traffic without air conditioning. And that's in the middle of the night. Do not try to land during the day.
Your hotel
Cairo is one city in which you should never skimp on accommodation. Only stay in a five star hotel. Even then most of them are completely awful. Stay in the Marriott Zamalek. This hotel is so full of people 24 hours a day that it feels like watching a rugby match. Nevertheless things there do work. Restaurants serve food. Bars serve alcohol. Nobody will scream at you because you are wearing immodest clothing. You can even walk out of it (although we will come to that).
Getting around
Are you sure you want to get around Cairo? It is the biggest and dirtiest and noisiest and most unpleasant city in Africa. Any journey out of your hotel will involve your becoming immediately covered in sand and dirt. Or driving in a taxi with its doors hanging off, etcetera.
Better to stay in your hotel and not leave.
Cairo is full of tourist attractions, but they are all filthy, noisy, full of people ripping you off and/or making up ludicrous stories the conclusion of which is invariably a huge aggressive argument and your giving people extortionate amounts of money to get rid of them.
Five-star hotels may rent you a large car with some large men to get rid of everyone, but then those men will harass you instead. If you have the nerves, you are better off with the local taxis.
Going to meetings
This is a mistake. What meetings do you think you can usefully go to in Cairo? Ones with the government? No. Ones with private businesspeople? No. Both will just involve hours of bullshit sitting on a plastic seat in a dirty room without air conditioning while dirty noisy vehicles pump in smog.
Do not go to meetings in Cairo.
Visiting the pyramids
This is a mistake. They are hot dirty confusing and full of people who are expert in making your life a misery with a view to selling you something you don't want (e.g. camel rides). Stay away from the pyramids.
Eating out
Do not do this. The only place with a number of restaurants in close proximity of one another is the suburb of Zamalek. Even then it will involve long walks in confusing noisy hot environments full of people trying to give you misleading directions; and the food may be disgusting and/or covered in sand and/or unavailable.
Eat in your hermetically sealed hotel.
Going for a walk
Do not do this. It will be hot, humid, noisy, dangerous (try crossing those insane roads) and you will have a headache with five minutes.
If you are a single female, you may find that men openly masturbate in front of you as you are walking down the street. Obviously do not engage with these interactions. Just pretend it's not happening and pass on by.
Renting an apartment
If you do this then everything will break down (including the air conditioning and water); the place will be crawling with armies of insects; and lots of people will come to your front door to piss you off.
If you live with a member of the opposite sex, someone will call the secret police to report suspected fornication (a crime). This will cause all sorts of problems, such as being followed around, reported to your landlord, reported to your boss, reported to your embassy, and so on and so forth.
Buying food
Most supermarkets have no refrigeration. And it's hot as hell. Don't buy food. Only eat in restaurants (but see above).
Nightlife
This can actually be quite good, if a little eccentric. The city is full of nasty bars, nightclubs and brothels, full of the nastiest people you have ever seen. They are all open ludicrous hours. Get drunk. But get a taxi home. If the Police see you in the street drunk, they will arrest you. You may disappear into the Cairo penal system for several days or even weeks.
All the women in Harry's Pub are expensive top-end prostitutes. This is the only place we know of in Cairo where you will find such people. Everything else related to prostitution in Cairo is extremely bottom-end. You have been warned.
Beware in the Zamalek Marriott casino. It is full of Gulf Arabs placing huge bets on things. Do not sit at one of those tables or you may suddenly find yourself losing colossal amounts of money. (Entrance to gambling venues, which are very rare, is confined to foreigners.)
Cairo has a thriving homosexual social scene but it will take a friendly expat to point you in the right direction as local people will never admit it exist.
Do not touch the belly dancers, where you find them, or violence will ensue of potentially a very serious kind.
Sexual relations
If you approach any local woman with a view to talking to them in social circumstances, you will be beaten by the nearest group of men. This author was beaten round the head and kicked down the stairs by groups of men on several occasions for 'speaking to our women'.
The prostitutes tend to be Sudanese. Consider carefully the potential sexual health implications of engaging their services before deciding to do so.
Law and order
Stay away from all interactions with the Police. Egypt is a Police state. You may be arbitrarily arrested and who knows what will happen to you then.
Shopping
Although there are huge numbers of shops, there is nothing you could possibly want to buy in Cairo. You will see.
Days out from Cairo
Do not attempt this. You can try visiting the railway station; but you won't last very long there. (There is a bus station but it must count as the worst bus station we have ever come across in the world.) Or you can hire a taxi driver to drive you into the middle of the desert where people will suddenly emerge from nowhere to sell you things you don't want. Avoid these types of excursion.
Conclusions
Cairo is a pretty difficult city to live in. Think twice before you decide to live in Africa's biggest, dirtiest and noisiest city.
However, notwithstanding all the above, we cannot deny that living in Cairo is very interesting. It will blow your mind away.