[xtreme]

The biggest problem is having to deal with USCIS, at least until you get your green card. Simple things like renewing your driver license, getting a mortgage, filling your taxes becomes way more complicated and sometimes impossible. Depending on the type of your your visa, you may have to postpone your foreign travel or job changes while done paperwork is stick in limbo at the USCIS. And if somehow you get into a complicated situation because USCIS messed up your application (happens more often than you think), be prepared to be stonewalled or ignored while you pull your hair out trying to fix it.