The best thing about IDkollen is that it's so easy to get up and running. We mainly make use of their APIs and the setup is literally done within the hour if you're familiar with web APIs. Secondly I must say that it's worth the monthly fee. The service costs us a couple of pennies more than the monthly cost would be if we'd integrate directly towards BankID, but since IDkollen takes care of everything around hosting, certificates and maintenance, I'd say we save money using IDkollen.