Seems like a pretty decent deal at the moment given new prices for episodes 1-5 are around the £15 mark. This version includes 1-5 plus 6-8 once they are released, and they'd normally cost around a fiver per episode.
Doesn't look like PS+ is required, so a 45% saving for all.
Price valid until August 24th.
Remember you can get it even cheaper if you purchase a PSN card via CDkeys - currently £18.99 (http://www.cdkeys.com/playstation-network-psn/psn-cards/psn-card-20-gbp-wallet-top-up-gbp-ps-vita-ps3-ps4) so just over £18 with their 5% discount.