I'm a bit of a Classics nerd, and I've yet to find a film set in the Ancient world that impressed me. However, 'Alexander' was exceptionally bad.
It's badly written, badly executed, Alexander for some reason has an Irish accent while his mother has a strange sort of Greek accent and the rest of the Macedonians have British accents... It's just a mess.
And the way I see it, a film either has to be well-made OR historically accurate for it to be worth my while. 'Alexander' was neither. When I, as a 15-year-old girl, can pick out mistakes every two minutes, (like having him quote the Aeneid, which was written about 250 years after his death? Seriously?) then there is something seriously wrong.
Also, this website says that there was explict homosexual situations? Nope. Not the case. It should have been, but no. There was countless instances of heterosexual sex, but when it came to Alexander and his life-long lover Hephaestion, they barely even kissed. It was cowardly of the director and for me instantly made me dislike the film.
So I've kind of ranted and raved here, but my point is: don't bother. Complete waste of money. If you're interested in Alexander then go watch a documentary, and if you just want to watch a good movie... well, you need to keep looking.