Apparently Packt Publishing has just opened an online digital book library, PacktLib. The service provides access to over 400 books published by Packt. Compared to 9000+ books of O'Reilly's Safari that's a bit puny in my opinion. This fact is reflected in a major price difference between the services.
A yearly subscription to PacktLib costs around 130 euros whereas similar access to Safari costs around 473. It's important note, however, that Safari provides more subscription options. PacktLib provides currently only yearly subscription while it's possible to subscribe to Safari on monthly basis.
In addition Safari provides a limited version that allows the subscriber to access ten books fully per month. In that case the price of a yearly subscription is just around 199 euros which provides quite good value as compared to Packt's current offering.
Nevertheless I find Packt's initiative refreshing. It's nice to see some competition to Safari! If you read a lot of Packt's books and prefer digital, easily searchable format, 130 euros sounds like a good deal to me.
I do think that it would be nice to have more subscription options. This would be more feasible alternative particularly for students.
Both services offer a trial which I recommend checking out in case you are into digital books.