It's quite a bit more hassle than normal American tax paperwork.
Every foreign bank account or financial instrument over some trivial amount ($500?) must be reported. Foreign banks must report your holdings and gains using forms more burdensome than the usual American ones. Good luck owning a company: if Americans have controlling interest in a foreign corporation, their books must be open to the US or the corporation's income will be included in your own. The last time I saw one, the form to describe your foreign corporate holdings had a Paperwork Reduction Act notice declaring it expects it will take 2 weeks to fill out.
I think the absolute simplest case would be a 1040 (not 1040-EZ), along with the extra form for the FEIE. The FEIE has a 'bona fide resident' determination section which is up for interpretation. Two examples are given in the instructions, but the IRS will not tell you if you count as a bona-fide resident in advance (I have tried to get a determination here, and they just won't make one). There is, thankfully, a 330/365 days out of the country exclusion; just carefully fill out the form that lists all of your travel days to any country for the year.
If you live abroad, your 16 year old kid is responsible for serious fines if they don't do this for their first McJob (in theory; I've never heard of it prosecuted that way).
This was all a few years ago; some details may be inaccurate. But it's a serious amount of work, and it's enough hassle that a lot of foreign banks and financial institutions simply won't do business with Americans (which is yet another hassle).