Generally, syrah/shiraz is deep dark red, medium to high tannin and acidity with black fruit, blackberry, and chocolate notes. In France, you would find mint, eucalyptus, smoke meat, and white pepper notes. In Australia, liquorices, cloves, and black pepper. In south France and Spain, it is usually blended with other red grapes. The wine has animal and vegetal complexity (i.e. leather, wet leaves, earth) when aged. Don't bother with B.C. Shiraz, unless it's really cheap.
Shiraz is almost synonymous with Australia as it's dominant export grape variety. Hunter Valley, McLaren Vale, and the best region Barossa Valley are famous for the full bodied, soft ripe tannin, low acid (sweet), big personally, jammy tastes (with a lot of young American oak). On the other hand, Coonawarra and Central Western Victoria are a lot cooler and the Shiraz here is more peppery and less full bodied... sort of like syrah...
French Syrah is more elegant and subdued. Côte-Rotie and Hermitage in Northern Rhône is the classic region, producing some extraordinary syrah sold at astronomical prices. There are a few other appellations offering slightly inferior quality at better prices. I will write a separate post on this topic.
Then there is Chile, the dark horse, produces rich and dense syrah. You can buy these at $8-$20 range, which is great for cooking beef stew.