Tottenham signed Janssen from AZ Alkmaar last month, as announced on the North London outfit’s official website.
The Netherlands international has arrived at White Hart Lane with a strong reputation.
Janssen scored 27 goals and created 56 chances in 34 Eredivisie matches for AZ during the 2015-16 season, according to Squawka.
The 22-year-old had a pass accuracy of 73% and a shot accuracy of 55%, and won 21 headers, 35 dribbles and 21 tackles, according to Squawka.
Former Newcastle United manager Souness has suggested that Janssen is a gamble signing for Tottenham.
The former Scotland international midfielder has used the example of Manchester United winger Memphis Depay to make his point.
Depay joined United from Dutch club PSV Eindhoven in the summer of 2015 for a transfer fee reported by BBC Sport to be worth £31m.
The Netherlands international winger arrived at Old Trafford with a strong reputation, but he struggled to live up to expectations in his first season in the Premier League.
The 22-year-old could score just two goals and created only 12 chances in 29 Premier League matches for the Red Devils during the 2015-16 campaign.
“They’ve signed Vincent Janssen on the back of one good season at AZ Alkmaar,” Souness wrote in The Sunday Times. “That’s a gamble when you look at Memphis Depay, who was meant to be the best player in Holland when he went to Manchester United. It’s not the strongest league in Europe.”
Tottenham will kick off their 2016-17 Premier League campaign with an away game against Everton this coming Saturday.