Not very, in my experience. Although they were very helpful on exporting goods, every other question I had was either answered incorrectly (!) or met with 'we can't give legal/accounting advice' - which is understandable but I did tell them my questions beforehand so they could have avoided a wasted meeting.

They then tried to persuade me to use a particular SEO company - so I left.

Your experience of Business Link and what it can offer you is largely down to the postcode that you live in. In the good old days of the 90's and 00's the Government would throw resources at an area based on some criteria it had set. Year on year, postcode by postcode this would change.

The site itself isn't bad, there's a fair amount of decent advice on there, although nothing that isn't really available elsewhere.

Fairly hopeless. It's less about startups/business than it is about people becoming self-employed. I've tried it in various areas, from the shit to the affluent - always abysmal.