My understanding - difficult but doable. I have one potted specimen but I'm just letting it grow wild to build the trunk. I also have one in the ground.
Problems I know of...large compound leaves, susceptible to fungal diseases, relatively short-lived. If you do a google image search for "albizia julibrissin bonsa" you'll find some examples (though some of the pics are of similar appearing tropical mimosa). Bill Valavanis had a really nice one that can be seen at http://artofbonsai.org/galleries/valavanis.php (scroll down to next to last image).
I have probably 30 mimosas of varying sizes but they do take container culture well and are very vigorous so they give you something to work on. In my eyes they will never make world class trees but theyre fun and the flowers are beautiful and smell awsome.