Manhattan? Speaking purely as an Australian here, but one who is in favour of the Westminster system as compared to the American “separation of powers” system… well, like most things in life there are pros and cons to every thing.
Some of the Pros attached to the Westminster system, in my humble opinion are as follows.
(1) The leader of a “Westminter System” country is rarely a “Johnny Come Lately” as it were. Our current Prime Minister started out 20 years ago as the Treasurer, which is a vitally important role in shaping, and managing fiscal policy and tax law etc. He then spent quite some time in the wilderness during stints when his party was the Opposition, and also because he definitely was NOT in favour with the National Executive of that party. Indeed he was banished to the backbench for quite some time where he didn’t even have an Opposition Portfolio at all. But all along, he was still a Member of the House of Representatives and eventually his star became in the ascendancy once more. In American speak, I guess the equivalent would be like “moving up the ranks” until you become Speaker of the House, as it were. The difference would be, however, if you did NOT have the Presidential Office as a separate Executive Branch. Imagine if the President was merely chosen at any given time as being the leader of the party with the most number of members in Congress, and that President therein was able to choose his Cabinet Ministers from various “stars” in his party from Congress.
(2) Because the Westminster System doesn’t have a separate Executive Branch a la “The Whitehouse”, the voting public recognises that their vote in Federal elections chooses “the party” to hold office, and the makeup of who will fill what roles is clearly known by the electorate before that election. The Cabinet Minsters (and the portfolios they hold) are all existing members of the House of Representatives, and some of them might not even be able to hold onto their local electorate - and the Opposition has a shadow cabinet already announced too, with Ministers holding “shadow portfolios” as well. In effect, the electorate gets to decide on which “team” they would prefer, as averse to which “man” they would prefer - but there’s a lot of overlap obviously.
(3) Each party in a Westminster System needs to assemble the brightest stars possible to form that “team”. If you’re in Opposition, question time provides an opportunity for those “Opposition Shadow Ministers” to actually second guess the official Cabinet Minister - after all, not all questions are directed at the Prime Minister in isolation. There’s quite a lot of prestige in being a very smart and insightful Opposition Shadow Minister who can ask tough questions, and indeed, “Parliamentary Privilige” means that they’re allowed to introduce some pretty damning evidence without any fears of libel. It’s not good etiquette to abuse “Parliamentary Privilege” though, and the unwritten rule is that wives and family personal matters are totally off limits. Nonetheless, question time provides the electorate to guage the various merit and acumen of both teams, that is the incumbent, and the Opposition. And I honestly believe this makes for a more informed electorate all things considered.
Certainly, one major “Con” which is attached to the Westminster system is that occasionally a Prime Minister’s authority can be diluted by not being able to act in an unfettered manner. This can be a good thing OR a bad thing depending on how you look at it.
Also, if a given country starts to have a third (or more) major party which makes the concept of “us or them” much harder to delineate, then you run the risk of shaky coalitions etc and politics creeps into the process of running the country, which can be a bad thing if it gets too unwieldy. In my experience, Westminster countrys which primarily have two major parties with just some crumbs scattered amongst your “independants” - well, they seem to be the ones which function most smoothly.
Unlike Italian or Isreali politics for example.
