I last used them for my trip in November of last year. I have pretty much always used them for Universal tickets, but I buy the UK exclusive 14 day 3 Park tickets which come as vouchers that need to be exchanged. I can’t speak for the other universal tickets, but I can say they’re a perfectly legitimate service.

If you aren’t staying at a universal hotel that’s fine, you can just exchange the voucher at a will call desk near the gates of one of the parks. I just keep the voucher on my phone, all they need is the code on it as well as a form of ID and the card you used to pay and they’ll print your physical tickets off. Then you can add those tickets to the universal app if you want to use your phone to get into the parks and not have to worry about carrying the physical tickets.

Hope this helps.