I borrowed a friend's TM21 for a few months and had a whale of a time and I've also used the more modern TM31 on a fair few occasions.
I guess the best way I can explain one is that first and foremost it's a fantastic piece of kit, but one that don't really fit in to a standard kitchen set-up. You have to really adjust your cooking methodology to suit a Thermomix and it's only then it starts to show its pedigree.
The claims that it can replace a 'food processor, bread machine, coffee grinder, grater, electric whisks, steamer, juicer and slow cooker' are pretty accurate and there's not really a weak area in its armoury when it comes to that, but it's really the time-saving element that makes the most sense.
Being able to prep and cook something in the same machine at the touch of a button (sort of) is where they really shine. One of the first things I made was a pea puree/velouté and that knocked my socks off. I'm a dab hand at making one in the normal way, but in the Thermomix it took about 10-minutes from start to finish and blew me away in terms of texture, taste and appearance.
You can really start to appreciate why they are so heavily relied upon in professional kitchens, but if you get your head around how to make best use of one there's no reason why it can't become equally indispensable at home.
Quite a few pro kitchens have them and swear by them. Curious!
I'd suggest that was more about their predictable results and ability to just 'get on with the job' than anything else. Vorwerk have really pushed them in commercial kitchens as well - the discounts and deals they get offered to use them is staggering.
I didn't find anything that I made in the Thermomix I was borrowing couldn't have been done 'by hand' - but it would be easier, quicker or just plain
better in the Thermomix.
And then you've got to ask yourself; is the reason I'm not making these things because I can't be bothered or because I just don't really cook/eat like that? As the answer to that question will determine whether or not a Thermomix makes sense.
If they're as good as the marketing claims then I'd imagine there'll be more reasonable domestic units out in the not too distant future, as happened with sous vide.
The Thermomix has been around for years and nobody has bothered to make a more domestic-focused competitor. It's just
that good at what it does.
Admittedly there are various 'alternatives' on the market to a Thermomix, but none of them get close in terms of what the TM31 is capable of. It's the design of the thing more than anything - and that's very tightly patented.
And in my opinion, home sous-vide has still got a long way to go before it becomes more popular. For me, the machines need to halve in price and double in usefulness.