The stuff in the cans tastes like ass so I'll pass on that....
i must disagree with you.
some canned beer kits can come out quite excellent, if you follow the directions and buy fresh.
if the can is more than 3 or 4 months old, don't bother.
but honestly, i have made some very,very,very,very,tasty brews by boiling dried malt extract and hops and then dumping in a coopers kit at the end.
one of my all time favs was an imperial stout i made by boiling 6 pounds of dried malt extract, 2 oz. of challenger and a half a pound of molasses, then after 60 minutes, turning the burner off and dumping a can of Coopers stout kit.
just my own input....freshness, and making sure not to boil the no-boil kits makes all the difference
on the other hand...extract brewing is more expensive.
but, it can be worth it if you really want to brew and can't dedicate the amount of time it takes to do a full mash, sparge and boil.