they are part of coral, who are the 3rd biggest bookmakers in the UK. cant speak from an affiliate viewpoint, but from a players view they are perfectly reputable and safe.
their strength would be the sportsbook side, i have played their casino, it uses chartwell software which im not especially keen on, but havent used their poker yet.
eurobet is the brand aimed mainly at europeans, coral at the uk market.
id expect any problems to be with regards to miscommunications or inefficiency rather than honesty – although thats not much of a consolation!