I can no longer recommend Trivago. Their advertising got to me and I used the site based on their ads. However, my recent experience was a total dud.
I booked a hotel and it turned out the booking agency (Hotel Power, which I definitely do not recommend) was a place that automatically enrolls you in a "free trial."
While not an outright scam, the free trial means that you, the customer who absolutely never asked for this, are enrolled in some VIP concierge service that you have to pay for after 90 days. So I then had to waste my time cancelling this "VIP service" I never asked for. Trivago did not warn me it was sending me to a "members only" booking site. I hate having to waste my time and I hate it even more because I felt that the booking site that Trivago led me to was totally misleading.
Also, in case you are wondering, there is nothing VIP about the Hotel Power experience. Nothing was wrong with our reservation on Hotel Power, but if they actually want a customer they could have done something to show why they matter, like get a kickback from the hotel for free water in the room, or a free drink at the bar, or free early check in or something. Nothing special, not a service I'd pay for.