Although Yell can be a great directory to register your business on, some of the additional services that they offer are not so great. For example, if they build you a website it's likely to be from a limited number of templates, it will be relatively expensive and most importantly, YOU WON'T OWN IT!
I've recently built a new website for A Carling Plastering Services, the old site was built by Yell, which meant that we couldn't use the old domain name, as it's owned by Yell. Despite having paid for the website to be built and a monthly fee, A Carling Plastering doesn't own the website or the domain name, its held by Yell under copyright!
We've bought a new domain name, 2 years hosting and SSL certificate for under £150, the website would have cost £699 with Yell and because it is a more substantial website, the monthly fee would have been higher than the £40 per month the old website cost, but the new website is 100% owned by A Carling Plastering Services.
Analytics were added as standard; data is key to good digital marketing so adding analytics is essential, this then allows you to see what is working and what needs improving, but with Yell it's an extra cost. The website is very responsive and can be edited to display exactly as you would like it on tablet and mobile phone.
Sadly the focus that Yell has on sales, does not seem to be backed up by the aftersales support. We have so far made two requests to Yell to remove the link to the old domain name in the directory, as this website no longer exists. We're not sure whether they're being difficult, because they built the old website or just incompetent. If you research on Google you can find many instances of Yell over charging businesses and reports of poor customer service.
To summarise, as a directory I think they're pretty good, in terms of additional services: they're excellent at selling them, seem expensive for what they offer and a nightmare to deal with! So, find yourself someone who when designing your website, will take time to understand your business and it's competitors, will represent your brand and produce you a website that you're proud of and that you 100% own.