I've had an account with them for the last 5 years and have no complaints.
Fees are just 4 euro for small purchases of EU based ETFs.
All account management, trading, customer support is done through their website, that's how they keep costs down. I needed phone support only once, that I can remember, for a login issue and it was sorted out promptly.
if trading 10000€
IB = 0.1% of 100000 =100€ =>29€ (max trade fee)
Degiro = 2+0.02% of 100000 = 22€
if trading 10000€
IB = 0.1% of 10000 =10€
Degiro = 2+0.02% of 10000 = 4€
if trading 1000€
IB = 0.1% of 1000= 1€ ->4€(min trade fee)
Degiro = 2+0.02% of 1000 =2.2€
So, it seems that the broker with the lowest fees depends on the volume of the trade
IB sounds like a more solid broker to me when you put the whole package together