Looking at what they offer, to get international notam data would be £40/year and that isn't worth paying IMHO.
Everything else they do I can get from a combination of Avbrief (which offers more weather data than Skybook) and all the various free sources.
It looks a very UK-centric site.
Unfortunately there isn't a site that is any good (alone) for a VFR+IFR pilot who flies abroad. One has to use a variety of sites.
I am very suprised that Avbrief have not implemented a route notam briefing.