If you look at the geography and the prevailing trade winds, it's pretty obvious that to sail around the World today (if you start in Northern Europe) then you have to sail South across the Atlantic and then either go East or West.  Going East is far more sensible.

With this reality in place, it becomes likely that Brazil and South Africa are going to be two of the first ports of call. Going East, Western Australia makes sense and then you have to get to China for the Qingdao stopover (which is not to be missed for spectacle).  Whilst in Oz though, it seems appealing to compete in the Sydney Hobart Race so continuing East, either around New Zealand or Tasmania, Sydney has been a regular stop for the last few races. Before that New Zealand and then Australia's Gold Coast were stopover ports.

Leg 4 is, therefore, usually Western Australia to East Coast Australia, perhaps including the Rolex Sydney Hobart after Christmas and then a short hop back up the East Coast. The leg needs to advance the race to China. Going East around Australia makes some sense as there's a large continent on our doorstep.

Because it's Christmas Sydney Hobart is a possibility. Then you need to go North to get around Australia and back towards China. This means lots of races The advantages to Leg 4 are, in my opinion, as follows;

PROS

• More than one race per leg (usually). The leg has previously been split into as many as 4 different races. As a 'legger' one of the big advantages is that if one race goes wrong due to breakage (people or yacht) then you still have more bites at a podium.
• In the past, there have been some great stopovers on Leg 4. Plenty of fun stopovers (and a long stopover in Sydney sometimes) makes for a fun time. However, I noticed the fleet has just had copper anti-fouling treatment, so the Sydney stopover may not be as long in future (they used to lift the boats to apply antifoul at this halfway stage).
• Southern Ocean! You get to dip into the Southern Ocean again. A real box-ticker for most sailors.
• Sydney Hobart. OK, so you've already done more Southern Ocean miles that a Sydney Hobart racer before you get to the start line, but the race has real kudos and that first reach down to The Heads in Sydney Harbour is a real blast and worth experiencing.
• Weather - It's the Southern hemisphere's summer when you're there, so generally the weather is good. OK, the Southern Ocean always has the potential to be a cold and ornery beast - but the sail North is usually good and the Coral Sea in January is a nice place to be (except for the Cyclones).

CONS

• Australia is a long way from the UK. If you're resident in Europe, Oz is an expensive return fare if you are doing one leg.
• You are away from home for Christmas... Of course, some people might see this as a benefit!
• No Ocean Crossing - You get the Southern Ocean. But you don't get to cross an Ocean. If that's important to you, this may be a deal breaker but read on..
• It's Cyclone season. These monsters are very predictable and the race works around any forecast problems, but this can change the timetable. That said, this is normally relevant to Leg 5, not leg 4.

All in all, I'd say Leg 4 is a good leg. It has several races, it's set in a great part of the World and there are iconic events and locations all around you and a mix of conditions. What's not to like?