Twitter‘s CEO Jack Dorsey has promised to overhaul its ad offering to make it a more attractive proposition to advertisers after admitting it was previously too complicated, making it hard to see its point of difference.

Speaking in a Q&A session with WPP boss Sir Martin Sorrell at the Dmexco ad tech conference in Cologne, Dorsey claimed that while it has a very strong differentiated business advantage, it hasn’t clearly communicated that with marketers and agencies. And that failure can be seen in its results. Revenues were down for the first two quarters of this year for the first time on the back of stalling user growth.

When questioned by Sorrell over whether the experience had been too “clunky” for advertisers, Dorsey admitted that it was and said the focus has been on simplifying…