I have never been to Hexham in my life, but if I was a Passenger living in that area I know who I would travel with, and the would be Go North East, I don't see how the 685 can even compete with the 10/X84/X85 when Go North East are offering the following Ticket Options with the Bonus of Free Wifi and a Bus Service which turns up on Time, and clearly as Dan Mentioned that Passengers in Hexham are Praising which Go North East are giving them.

Ten Weekly Saver - £14.60

7 days unlimited travel on the TEN and Toon Link 11 buses between Greenside, Crawcrook, Ryton, Blaydon and Newcastle
Toon Link 32 buses between Blaydon Bus Station and Newcastle

Ten Weekly Saver Plus - £21.80

7 days unlimited travel on the TEN and Toon Link 11 between Hexham, Corbridge, Branch End, Prudhoe, Ryton, Blaydon and Newcastle.
Toon Link 32 buses between Blaydon Bus Station and Newcastle
Valid on Tynedalexpress X84 / X85

whereas Arriva are offering - Info from 685 Timetable

Day Ticket: Adult £7.30 - Child £5.00 - Concessions £5.50 - Family Two Zone Triple Ticket valid Newcastle to Hexham £13.00

Regionwide Weekly Saver £26.00 - Family Two Zone Triple Ticket valid Newcastle to Hexham £21.50

No doubt prices are same for Stagecoach as it's a Joint Operation, Overall from a Passenger Perspective, I would say you get better Value for Money using Go North East.