I can't speak for others, maybe some had issues with them. In my case it worked as advertised. I never had to unlock a phone before, and this experience thought me a couple of things:
- eBay code sellers advertise "Most phones unlocked in 24 hours"
- MobileInCanada didn't advertised any time estimate, but my code was delivered in 24 hours.
- From what I read, most if not all unlock services use the same database+algorithm and takes about 24 hours to proceed, even those who advertise "in under 1 hour".
- Have I found about eBay sellers and their lower prices afterwards. Maybe MobileInCanada is pricier than some eBay sellers, but at least for me, it worked just fine.