A hostile takeover for a small-time company like AMRN is a bad sign. Especially for a CEO that isn't a super-dedicated founder in love with his business and has previous history of selling his previous company.
It usually means that either the BOD has pie-in-the-sky unrealistic expectations of what the company is worth, or nobody is willing to pay that much of a premium, so the acquirer is making a play to the shareholders at large with a sensible, small offer. Usually somewhere in between the two.