I am reliably informed......
....that SAP is used for their billing systems by npower and Scottish Power, who are rated the WORST two energy suppliers, both being unable to produce bills in a timely manner.
'Nuff said.
Rampant cloud growth struggled to offset falling profits for SAP, Europe’s largest software company, during the firm’s second quarter. Post-tax profits tumbled 16 per cent to 469m euro ($508.2m) while total revenue increased by a fifth, to 4.9bn euro ($5.3bn) for SAP’s three months to June 30, 2015. Earnings per share fell 16 …
It's also used by British Gas (http://www.computerworlduk.com/news/strategy/british-gas-completes-sap-crm-billing-system-migration-3585373/) which is highly ranked...
It's all on the implementation. And that's done by Accenture, IBM, ATOS etc. Granted: SAP is a monster, but you also need to consider who you use to tame the monster.
Talking of Accenture, in 2010 they tried to sue because their British Gas implementation of SAP failed (http://www.cio.co.uk/news/supplier-management/accenture-lose-appeal-in-british-gas-case/).
It's kind of like blaming Microsoft if an application you downloaded crashes because it doesn't handle an error.