I have gotten a lot of traffic and traction off of Booking.com and filled a lot of empty dates that weren't coming in on the Airbnb/VRBO site. BUT - and this is a huge but - there are some serious caveats you need to keep in mind:
1. You need to have your own ability to take payment. We have our own portals - we have all the major stuff already because of our LTR company - Stripe, Square, Zelle, Paypal, etc - but if you don't have this, you will need to get it to use Booking.com. Eventually, I'm told, you get to be a gold star type host and they'll collect payment for you, but no one can tell me when or how this will work because...
2. They're a foreign company and not very easy to work with. Reps speak rudimentary english at best. You will spend some time on the front end waiting on long holds, and you'll do this because...
3. They don't charge the guest's credit cards, only take them to book on your calendar - so if the guest cancels during your "no cancellation" period, you are SOL because you don't have the CC number and can't see the CC number. Eventually, I'm told, you can see this once you're a gold-star type host, but until then the info is masked so you have no way of pre-authorizing or charging the card. You have to physically contact the guest yourself to get their credit card info to have them pay through an outside portal (like those I listed). And because they don't actually charge the CC and you have no way of charging the CC until they pay...
4. You get a decent number of scam and "lookey loo" bookers, because they know they haven't actually paid for anything. This ends up being a problem because once someone books, they've locked you into that booking according to booking.com's rules - you can't cancel until they day they don't contact you with a valid credit card.
So I have had my battles with them. I've done a lot of traffic and stays with them so far - probably 50% compared to 50% total Airbnb/VRBO - but I have worked for that money for sure.
If you use them, I would highly recommend blocking out high-value dates on their platform and leave them open on the other platforms, and either manually sync your calendars or just leave the booking calendar off of VRBO/AirBnb, because you don't want some BS booking clogging up Christmas, New Years, etc.