I feel the 357 is at its best when used on thin skinned animals under 150 pounds at ranges under 50 yards with optimal loads and broadside shots. Put much of an angle on the shot and the range lessens considerably. With the standard factory loads, bring the range in to 30 yards under the same optimum conditions. The same ranges would go for smaller boars as they are built much tougher than deer. Largish boars, over about 120 pounds or so, cut the range down by half and make sure you use ammo designed for hunting rather than the stuff commonly found on the shelf.
I've shot a few deer and even a couple of bears with a 357 and have not been overly impressed. It was designed as a personal defense cartridge that was pressed into the big game hunting arena. As such, shot placement is critical with this round as there is little room for a less than perfect shot.
Quit being an a$$hole. You asked a very broad question, and I gave you a bit of Gun-Nut humor followed by an answer. Then you asked about boar, and I answered, and you leave a smart a$$ comment. If you want an answer, ask a question :?