I've been using Revolut Ultra for a whole year and the question in the headline is actually one I've been asking myself.
Was it worth it? I can give two answers. Polar opposite but identical.
Answer one would be, 'yes as long as you...'
Answer B would be, 'no unless you...'
It's not cheap
The first worth noting is that this isn't a cheap plan.
I'm presuming pricing will vary depending on your location but, for EEA/EU-based users, it's between €45 and €55 per month.
You get a few perks, though.
Including two that are pretty useful if you travel a lot, which I do, and which is the main reason I'm sticking with it.
I know I'm supposed to tease the answer a bit more but yeah, there's the answer. Is it worth it? Yes, as long as you travel a lot. And also, no, unless you travel a lot.
But here's why.
Key perks for travellers: lounge access

Revolut Ultra comes with a very long list of perks that range between 'oh wow that's useful' to 'what the duck am I supposed to do with that?'
One of the key ones is you get unlimited access (for yourself) to airport lounges that support Dragonpass.
Very nearly every airport in Europe does, and then some in other continents as well.
There are two things to note, though.
First, unlimited free access is only for you. You can bring guests but it'll cost you a flat fee of €24 per guest.
Second, some amenities may not available. Some airport lounges, for example, won't let you use the shower unless you're actually flying business or, in some cases, unless you top-tier Amex cards. Anything else (Dragonpass, Priority Pass, etc) will 'only' give you access to food, drinks, etc.
Not exactly a deal-breaker IMHO, but worth noting.
Also, on the topic of airport lounges, some people think they're unnecessary, and I get it, but the reason I use them is the way that air travel works, you kind of have to waste time at the airport anyway, and so you might as well do it in comfort.
Also, airport food can be pretty bad and pretty expensive, and so you can remove both elements (or at least the cost) with lounge access.
For reference, a pint of beer at Istanbul Airport can easily cost over €20 (not a typo), and with lounge access you get as many as you can drink for free.
Most airport lounges also welcome walk-ins, but it'll cost you anywhere between €35-€40 (the really cheap ones) and €100+, so yeah, that's a perk I'll happily keep using.
Other perks for travellers: eSIM, insurance, miles, zero fees

With Ultra you get a free eSIM that works in most countries in the world. I've used it in Europe and Istanbul and the US. It's a long list (about 100+ countries).
You get 3GB, which is not a lot but nothing to sneeze at.
You also get travel insurance, which is particularly useful if you're travelling to countries that list medical/travel insurance as a strict requirement for entry.
You also get miles. I'll talk about the way 'RevPoints' work in a second but the bottom line is you can convert those into miles (1:1) with most major airlines.
Also, Ultra users pay no fees - zero - on transactions that require currency exchange in real time.
It doesn't matter where you are, it doesn't matter what you're buying and what time of day/night it is, there are zero fees.
And that's quite useful because I know people who keep getting completely butchered by fees. And I also know this because I live in a non-EURO country and I see people whose main account is in EUROs that keep complaining about paying €3 in fees for a €2 transaction.
How do RevPoints work?
With Ultra, you automatically earn 1 RevPoint for every dollar you spend.
And you can top up the pot with various challenges (some are simple and don't require spending money), or by buying RevPoints in bulk, or by purchasing services and products via Revolut.
Example, you may find promotions for, say, Publish0x Airlines, and if you buy a Publish0x Airlines via Revolut you may 2x, 5x, 10x your points.
You can redeem point for the usual useless shopping, but also for groceries, hotels, eSIMs, airline tickets, and so on.
Other stuff
Revolut Ultra includes several free subscriptions, the most useful of which, for me, is for a photo editing app I use daily, plus of course you've got various other things like NordVPN and three monthly access to WeWork spaces.
So is it worth it?
The monthly fee is pretty high, but you do get some of money back directly with the eSIM and subscriptions (IF you use them). RevPoints are useful, but obviously tilted way in favour of Revolut, not the user. Realistically, if you use your Revolut card for absolutely everything, you get the equivalent of a single-digit percent cashback on your yearly expenditure - more or less.
If you're a hardcore traveller (I've used lounge access about 30-35 times this year), go ahead, if you're not, it's probably not worth it.