I was there in 1998 just a couple of weeks after a big shooting of tourists down south in Luxor. The result was the number of tourists in Cairo was greatly reduced which had a good and bad side.
If you're not used to it the harrassment from street vendors can start to irritate - but this isnt as bad in downtown Cairo as it is around the Giza plateaux or further south in Luxor.
Despite being a city with huge poverty problems (like any large developing world city), Cairo felt extremely safe. If you can manage to cross the road without being mowed down by crazy beeping taxi drivers then you stand a good change of getting through the experience unscathed.
A travel companion of mine was feeling adventurous one night and went out for a stroll around downtown Cairo at about 3am one night looking for intrigue and adventure.. He wasnt sure what he woudl find - but verntured out with very little of value and just thought he'd try and find some seedy and interesting nightlife. He wandered aimlessly around for a while and found himself down a poorly lit dead-end alleyway. He turned around to head back towards the main streets and found 2 suspicious looking characters following him. At this point he prepared himself for conflict (and presumabley the intrigue and adventure he was looking for) assuming that anyone following a tourist down a dark alley at 3am must be up to no good. The strangers walked up to him and asked if he was ok - and what he was looking for. When my friend replied that he was looking for a club or bar the guys apologised for their lack of knownledge of such things and offered my friend an apple to keep him from getting hungry! They then went on their way and no harm came to anyone!
In general we found Cairo to be a very friendly city - there were army guards on almost every street corner with machine guns who were very friendly to any tourists and everyone seemed genuinely keen to help us get around and find out what we needed. When 7 of us took a bus trip to Giza (after working out which bus to catch, which was an ordeal with bus numbers all being in arabic) for the obligatory trip to the pyramids we got chatting to a local guy (who was keen to practice his english) and we ended up being invited round to his house for tea and a snack (and a fascinating look at genuine local culture).
"The Cairo Museum" - is without a doubt the worlds largest collection of Egyptian antiquities - however, the organisation and explanation of all the stuff leaves a great deal to be desired. The effect is that theres a whole building with piles and piles of very old stuff.... great if you really want to spend time looking at it - but theres very little to be learnt from expanatory notices in the way that you might expect of one of the worlds leading museums.
Of course all this experience is just based on a few days on a backpacker style holiday... and I'm sure there are plenty of other sides to Cairo.
I'm sure visiting for a conference would be a different experience altogether. We did pop-in to the Cairo Hilton for a drink and noticed a very definate hint of pompous colonial sophistication of the type you get in places like this, Singapore Raffles Hotel, The Victoria Falls Hotel etc etc etc... but the prices were so extortionate we couldnt even afford to sit down and have a drink!
I'd say - if you're going to Cairo on business, take the time to get out of the hotel and taxis and WALK around for a bit. Nothing beats an aimless wandering around a few streets of a city for a hour or two for getting a feel for the place.
Apart from the pyramids , I though the city was over-populated, very dusty, sand storms appeared to hit every other hour and the shopping - you are expected to drive a hard bargain, so the prices are really inflated. Depends on whether the customer is used to or even like s bargaining. After one or two negotiaions I gave up. I'm sure I ended up paying too much. Travelling by boat on the Nile is supposed to be an unforgettable experience.
I've never been to Cairo, but I have lot of Egyptian friends.
Only once I got in trouble by asking a guy to show picture of his sister (note I'm a married woman, and could not have any sexual thoughts). I learned that unless they offer to show photos theirselves, never ask, also never ask details of looks of family members, it is much much worse if you are asking about family members of opposite sex than yours(I believe this applies to muslims only, but I would still be careful). Hovewer, unlike in many other countries, it seems ok to ask them about their religion.
Also they told me that there are tons of forighners in Cairo that behave differently (ex. topless girls on beaches), but everyone takes that as normal. Seems they would frgive a lot to foreigners.