Billpay just seemed like too much hassle and an extra unnecessary level of indirection compared to using online banking to pay bills.
Well, each to his own, as they say.
I actually prefer the level of indirection - I have one Direct Debit mandate on file with my bank, which allows me to pay all my bills using BillPay.ie. I can also use my Laser card without requiring a mandate.
I plan to switch bank in the New Year and the BillPay.ie facility will make it easier for me to pay my bills from a new bank account, without having to change multiple mandates.
I also like the central bill history feature - I used this to track how much eircom had fleeced me before I finally decided to switch telco (to EsatBT).