If you haven't done so already, I suggest you read the "sticky" at the top of this forum, which lays out a lot of the rules.

http://www.flyertalk.com/forum/showthread.php?t=338667

[One thing I notice looking at it quickly is it says you can have up to 20 segments. That's no longer true - it's now 16 segments. Also, surface segments (e.g., IST-DXB but also even LGA-JFK) now count against that 16 segment limit, although they don't count against the continent-by-continent segment limit (i.e., 4 flight segments in each continent, except the U.S. where you're limited to 6 segments)].

The rules are also on the oneworld website, in a PDF document -

http://www.oneworld.com/content/libr...rule_sheet.pdf

As for the "missing hidden costs", they are of course (a) the time you can spend travelling the world on these tickets and (b) the hotel (and other) costs incurred along the way .... You can have as many stopovers as you like (except in the continent of origin, where you're restricted to two) so ideally you fly stopover-to-stopover, minimizing places that are just connections, and get to visit a lot of good places...

There are many posters in this forum who are intimately familiar with all the rules etc., so if you have questions, just post away and somebody will know the answer.