Done just under a 1000miles in it so far and loving it. Had a Mk1 diesel before and that was excellent - Cheap to buy second hand, astounding fuel economy, bullet-proof reliability. Probably last of the bullet-proof diesels before emissions controls made them less reliable than petrols.
Was forced to change due to Sadiq Khan and his money-grubbing decision to penalise the diesel cars that his own party convinced me to buy in the first place.
Tried the Mk3 Yaris hybrid; Hated it - Horrible to drive, gutless, no better economy than a normal petrol unless you drive without any regard for fellow road users, had none of the features that made previous Yarises special like the collimated dash unobstructed by the steering wheel, or the sliding rear seats, and very expensive even 2nd hand.
Ended up buying a Mk2 1.33 which had similar economy and a bit easier to take on motorways and only cost a third as much.
Got rid of it because it turned out to be the most unreliable Toyota I've ever owned (Engine drinking a litre of oil a fortnight, whole aircon system failed, gearbox failed). Was saving money for an EV but as I wanted something small, sub-4m closer to 3.7m, with at least 300 miles of range at 70mph, and everyone seems to be going the opposite with giant short-ranged land barges, ended up saying f-it and went all in on a Mk4.

Best decision I ever made - The car is great. Great to drive, and unlike previous generation hybrids actually genuinely efficient - Previous hybrids you had to drive them efficiently or the mpg would be awful; With this I'm thrashing it about and still getting 68mpg!
The steering feels good, if overassisted at lower speeds, and everything Just Works. I was skeptical about the lane assist but have been converted - It's like the Tesla Autopilot - Just turn on cruise control and the car will practically drive itself, including steering and braking! You still have to keep an eye on it as it's not perfect; I'd rate it as good as an advanced but overly cautious and easily distracted learner driver.
But it has made those long boring trips up the M1 with its many accidents and markedly increased closures (Thanks 'Smart' motorways!) far less fatiguing.
And if i take the fancy, flick it off and dive onto an A-road where the improved handling can shine. The car does feel a lot heavier than my old petrol and diesel cars, mainly because it is, but the boost from the electric motors and the lovely growly 3-pot even make that fun too.

There are a lot of things to gripe about in this car - the interior feels much more cramped than even the Mk1, because the roof is so low; The all-around visibility is awful - It may as well have no rear window; I can see why the reversing camera is standard! And the safety systems can get a bit annoying (But are a thing on all new cars anyway, and could be a lot worse!) and it is quite expensive...

But these aren't as important as one factor: Is it fun to drive, and for me this it is a resounding Yes!

The novelty of going full-bore away from the lights and out-launching everyone, and having the confidence to pull quick overtakes on country roads safely without needing to take a run up, which is something I've missed so much from my old Mk1 diesel, has put a lot of the enjoyment back in my journeys.
And if I want to take it easy, it does that well too, just flick the auto-cruise on and follow the car in front and let the car do most of the driving.

This is a b***** good car! If it wasn't for Sadiq Khan forcing me to drop my Mk1 D4D ahead of time and the Mk2 committing suicide I probably would have waited 3 more years before getting one of these at a more reasonable price, but even getting one at full price, now that I've driven it and gotten used to it experienced what it can do, I don't regret it.

In fact, the only thing thst soured me on the whole experience is the dealer.

Given how much money I was trying to throw at them, they just didn't seem interested, barely acknowledging my existence and often leaving me waiting for ages; Even got the order wrong, which they at least agreed to sort out with no extra charge for the missing bits.
Salesman barely talked to me or explained everything - If I hadn't specced up the car in previous research god knows what I would have ended up with.
Rarely available over the phone or called back, e-mails unanswered for days and full of errors, found I had to physically go to the dealer whenever I wantrd to check or clairfy something.
Literally the worst dealer experience I've ever had, and I've been to some proper dodgy 2nd hand dealers in my time!
And the salesman was one of the more communicative staff - The service department were even worse! I'm seriously considering driving 40 miles to the next closest dealer for servicing if this is how much they care.

So, great car, but find a better dealer than Jemca.