To use an interview coach - is it worth the money

I've had one provided by work as part of an outplacement programme, I found them moderately helpful, I probably could have found the actual information they shared myself fairly easily online (are you aware of the STAR(R) model for instance, very easily googleable if not), but it was quite useful to do a bit of role play/Q&A practice and get immediate/unbiased feedback on my style. If you feel it would help your confidence why not go for it?

I will say that not having got a job after 2 interviews absolutely doesn't mean that you must be hopeless and expressing yourself really badly, normally as a recruiter I would interview at least 3 people and sometimes as many as 5 for each vacancy and everyone I interview will have the skills/experience to do the job (otherwise I wouldn't have shortlisted them), so I would hate to think the 2-4 that don't get it go away despondent or thinking they've done something wrong. Often it just comes down to a minor difference in a desirable point or some niche area that one person excels in over another, or sometimes the more nebulous 'better fit' which is always really hard to explain in feedback to the unsuccessful candidates. So it may well be that something like that has happened to you and that's why the feedback you've had has felt a bit vague or unexpected?