This is dumb from both a marketing and SEO perspective.
SEO wise Google will index this notice for every webpage they index while the site is down for maintenance: this could damage SERPs.
Marketing wise this is an amateur move, what sort of multi-million pound business takes a website offline to do an upgrade.
Upgrades should be seamless, barely noticeable, NOT take a site out of action so customers can’t complete orders!!!
Continue Reading How NOT to Update a Website - B&Q Example