My feelings on this show have changed over time - I saw it for the first time around 2016 or so, and I've actually gone and watched nearly every season I can.
From season 16 on, with Andi Oliver as presenter, I absolutely love it. Nisha, Ed, and Tom are great judges and the humour is fab.
But season 15 was weird and all the prior ones are stodgy and stuff because the judges were very snobby people. Nice, but snobby and very white British.
But I'm Canadian and I watch on iPlayer. Like any British show aired in Canada, if you saw a broadcast version, they'd cut out way too much to take from 58 minutes in the UK to 42 minutes here.
The gist of the series is this: the UK is divvied into 8 regions, and in each, four chefs - previously just 3 - compete over 4 courses (and, since 2015/2016, two not judged tasters, a canapé & pre dessert, which are used for tie-breaking).
The show used to be 5x30 minutes a week, and now it is 3x58:00 instead. It's the same format weekly for 8 weeks - canapé, starter and fish on night one, main and pre-dessert and dessert on night two, and all 6 courses cooked for the judges by the top two chefs of that heat on night 3.
The first two shows each week have a mentor chef judge who will score all the courses after the day's cooking. The top 3 on night one continue on, with the 4th getting the axe. The top 2 go through after desserts on night 2. And on night three, the top chef then gets put through to the finals week.
In finals week, all 8 chefs compete to try to get one or more courses through to the "great British banquet." First night is starters, second is fish, etc. Fifth night, it's the big banquet and you see how it all plays out.
This year, the theme is British animation & illustration, and prior years have been things like great British science contributions, technology, rock n roll, TV, etc. I love watching the creative ways chefs meet the brief, which has vastly improved since season 1.
I also love how the show is never nasty or mean spirited. Chefs help each other and have lots of camaraderie. But that was not true in the early seasons, which I didn't enjoy. I think it changed by year 5 or so, under new directors who decided to make it competitive but friendly.
Now with the new judges and host, the personality of the show has caught up to the pleasant fun competitiveness.
This is one series where you can start watching at any point in the years it has been aired on, so I highly recommend watching seasons 16-18, if you're new to the show. (For whiplash, after you finish, watch the very toxic season 1.)