As an ongoing manga its hard to give a full on clear review as I do not know the direction Ohtaka will take. I can give my two cents on the story, till c.199, so far.
Magi is based on the one hundred and one nights, arabic stories from western and souther asia collected in arabic in the Islamic golden age (you can read ore on the wikipedia page for this collection of writings). The most popular and adapted are the three "Aladdin's Wonderful Lamp", "Ali Baba and the Forty Thieves" and "The Seven Voyages of Sinbad the Sailor" which were actually added by Antoine Galland and other European translators (wikipedia). They're actually middle east folk tales. Now we certainly can recognize the names of three very important characters in the manga. Ohtaka has definitely done her research and there are several references for these three tales in the manga. And for a fan of these cultural treasures I was pleased with the mangaka's imagination and use of the 'names' and 'items' brought into the story which flourished magnificently up to its 199 chapter.
The characters all differ in both status and upbringing all which is heavily emphasized in the manga and allows a lot of the main characters as well as very important minor characters to flourish and grow. It is also pleasant to read a manga which does remember its minor characters from time to time especially those involved with the plot. The art is very diverse from anything I have laid eyes upon but in time although at first I was a bit skeptic finding it too 'sketchy' at certain points but I learned to love it and also realized that the artist is slowly improving. Ohtaka's covers for the volumes are one of the most intense i have ever scene and I do love her used of colours, never had any complaints for them or the colour spreads which are gorgeous.
All in all Magi is a manga that everyone can enjoy and it is worth a try at the least.