I cook one or more every year around St. Patricks day when they are available in every grocery store.
You need to cook as the instructions say.  They need to be baked with lots of water, at a slower oven
for around 2 hours or so.  There is lots of fat on there, don't be afraid to trim some of the excess.
You can add potatoes, carrots and cabbage later on.  Yummy.
Brisket is a tough cut of meat, the brining and curing helps tenderize.
Don't try to BBQ it, that is for brisket...............