I'm someone who lives in an area with poor Orange coverage, therefore I have a triple sim-card cover for Orange/O2/Vodafone, usually keeping it on O2 at home but switching it to Orange where possible out and about.
As someone who was on the Orange Just Talk Original £50 voucher plan with discounted calls & text messages for over the last 2 1/2 years, as soon as this is gone, it's bye bye from me! Orange have been promising to improve their coverage around here "sometime this year" but haven't yet carried it out. With those charges I'd be better off sticking to O2 most of the time with their PAYG Original tarrif with calls at 2p at the weekend, and Vodafone for Voda-Voda calls. And as I hardly know anyone else with an Orange mobile phone except some ex classmates from university, it's really not going to be much use.
Sorry Orange, but while I've had coming up to three years of great service from yourself (apart from coverage at home!), once you scrap the £50 discount scheme on Just Talk you'll have lost a customer... and their might be more that follow