This beer is a traditional, strong version of Guinness, available in many overseas markets but not the U.S. That will change this Friday, when the beer will be launched in the U.S., or rather re-launched, since it was available in North America into the middle 1900's after which it was replaced by Guinness Extra Stout.
It is a bottled beer (no draft but I am not 100% clear on that as yet).
FES has more body, alcohol and hops than the other forms of Guinness. It is a survival of the 19th century Guinness Stout (as opposed to Guinness's domestic porter), which was the same 7.5% ABV. One of the forms of 1800's Guinness Stout, then known as West India Porter, was intended to last a long voyage, and Guinness FES is this same beer today, essentially. Hence its enduring popularity in the Caribbean Islands and other former UK possessions or areas of influence (e.g. Hong Kong, Nigeria and other parts of Africa, Malaysia, etc.).
While craft strong porters and stouts have become common and there are some very good ones, Guinness FES is still prized amongst beer fans particularly those with an eye on history. The one coming to the U.S. is made in Dublin I believe, and that should ensure particular quality. Some of the FES sold overseas is made locally under license and while always good, I always felt the Irish-brewed one was best.
The Guinness and stout fans on the board should at least try this, with due respect for its strength, and I suspect it will gain a few fans.