Twitter's chief delivers on updated features, but right mix is elusive

San Francisco

TWITTER's chief executive Dick Costolo has begun to follow through on his promise to reboot the company after the executive turmoil and product paralysis that dominated 2014.

In the past few months, Twitter has unveiled a blizzard of new features for its microblogging network, from a revamped home page that allows newcomers to browse popular posts by topic to automatic recaps of top tweets for users who don't constantly check their feeds. It even introduced an app, Periscope, that allows people to post live video feeds to the network.