Pros
Exciting and dymanic workplace, with lots of new ideas and a chance to put your own ideas into practice. The management structure can be very flat - which is great for getting to work with the top decision makers (but maybe less so in terms of promotion opportunities), and the team at the company contains some fantastic people, who are experts in their field but on the whole completely approachable and a pleasure to work with. There are so many new things going on it can be a bit overwhelming, but the overall feeling is of an exciting company with a great team of people.
Cons
As it is now a part of Daily Mail General Trust (which owns the Daily Mail, as well as papers such as the Evening Standard and Metro - and websites such as LoopyLove, Find a Property, etc) the company feels more 'corporate' as time passes - which can be a shame as it changes the culture. However, being part of a major corporate also has big upsides, such as the millions the group is ploughing into marketing the site and helping everyone realise just how powerful it has always been (though it still retains the flat feel of an independent company in many areas)