In those two respects, the country is really no different from other countries/cities that have huge, tightly packed populations - think of New York, Los Angeles, Paris, etc. They are all a bit overwhelming until you get used to the lay of the land and the local customs. What tends to make things a bit worse (for expats) in Nigeria is that unless we are of African ancestry, we stick out like a sore thumb.
Well it's different in the sense that in those countries you don't get (security escorted) taxis swerving around decapitated bodies on the drive from the airport, with everyone frightened to stop in case they get blamed/involved in some scam!
I'm sure that the majority of Nigerians are very pleasant and hospitable, it's just that there is a small but significant number who will look to scam or rob the obvious targets (for which 'white man' = obvious).
I'm sure that with time (which most of us don't have, ie 24hr slips as crew are it) that local customs become ingrained, and that the help of a local driver in the first weeks or so is highly desirable/essential.
The Ikeja Sheraton has improved considerably over the last 10 years, and (barring the frequent power cuts) is not dissimilar to many western hotels once in the rooms.
My overriding thought though, is that as a white person you will be a target and be very aware and cautious, even if that means getting ripped off by the hotel with their extortionate prices.
Just one last thought...on getting onto the crew transport with a 'security' guard, his welcome speech was/is words to the effect..
" hello, welcome, you are safe now .... I am a man"