The Bundesliga club agreed to sell Guinea captain Keita to Liverpool at the beginning of the season and the midfielder will complete his move to Merseyside ahead of the 2018-19 campaign.
Denmark forward Poulsen believes the Reds have made a solid investment in the 23-year-old, who has netted six times in the Bundesliga this season, adding five assists.
One concern for Liverpool boss Jurgen Klopp may be Keita's disciplinary record, with his red card in the weekend defeat to Mainz his fourth for club and country this season.
But Poulsen highlighted Keita's qualities, particular his goal in the 5-2 defeat to Hoffenheim on April 21, where he cut in from the left, beat three defenders and lashed an effort in off the post.
"I think that most of the fans of Liverpool already watched him play. He is a superb player on a very high level," he told Omnisport.
"He shows what he can do with the ball even if it's not going well for the team at this time.
"His last goal against Hoffenheim where he fakes out three people. He hit the post and then the ball went in.
"There are not many players in the world who can do that kind of thing.
"He is one of the few and not only the fans, but also his team-mates should be looking forward to that."