There are certain things that many of us are simply unable to do. My own surgeon was excellent about preparing me for the possibility that I couldn't tolerate some foods afterward, as well as advising me against certain foods (to contribute to the long-term success of my wrap).
The things he specifically warned me against were anything that would cause certain changes within my system, such as caffeine and alcohol. He also told me that I should never again drink carbonated beverages due to the amount of pressure the ingested gases would put on my wrap, or drink through a straw because of the amount of air that is ingested with the beverage.
The foods that he told me to prepare myself for being unable to ingest afterward were bread, raw vegetables, and "gassy" cooked vegetables. He advised that I could start trying them after 6 months, but to understand I probably wouldn't be able to stand them, and if they did cause pain from pressure that I was to avoid them completely.
Other things that people seem to have long-term difficulty with are pork and rice. I had trouble with pork for a fairly long time. As a low-carber rice isn't something I eat regularly (although when I'm going to splurge it is one of my favorite splurge-foods - with LOTS of butter!), but I didn't have difficulty with it. Maybe because of all the butter :).
He also told me that the majority of people who have this done will not be able to burp or vomit afterward - this should be considered a given. If you are one of those who are able to get air back up through your LES after your NF, you are in the minority. (NOTE: with time, some wraps will loosen somewhat and allow air to escape upwards; however, this means that stomach contents - acid - can also escape upwards, and this is not ideal obviously.) Remember, the intent of the Nissen wrap is to prevent the LES from allowing ANYTHING to go back up into/through the esophagus. That is the whole point of the procedure, after all.
For those who do find themselves able to burp, many are able to enjoy beer or sodas. (Definitely consider this the exception rather than the rule, however.) Whether this has any long-term effect on the integrity of the wrap, I don't know. I do know that with the fairly high failure rate - or shorter lifespan - of so many of these, my own choice has been to avoid anything that might contribute to an eventual failure. But some surgeons advise their patients that they may resume all normal activity and dietary regimens after complete healing. I'm just one to err on the side of caution with my own wrap :).
I've only mentioned the more common adjustments that most have to make after NF. Everyone has different results afterward and what is true for one will not necessarily be true for another. It may be wise to go into it accepting that we probably won't be able to drink carbonation or eat bread or raw veggies or caffeine or whatever...and then accept it as a wonderful gift if we find that we are indeed able to do so after we have healed.
