Wales finished runners-up behind Ireland after beating France 14-13 in Saturday's finale, an "ugly win" but one that helped them finish ahead of Les Bleus and England.
Wales defended ferociously around the impressive Alun Wyn Jones, who was back in the starting line-up after being rested last weekend for the game against Italy.
"We have got something to build on ... Some of the depth we have created in the squad is pleasing," said Gatland, who had made seven changes to his team.
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But 10 of the 15 players who started at the Stade de France in last year's Six Nations were on the pitch at kickoff at the Principality stadium on Saturday as Wales weathered the French storm in the second half.
"Second place is not what we wanted at the start of the Championship,” Jones said.
“But we aimed to come second when it was the best we could achieve and we did that. I’d like to think that we have developed more strength in depth than we had at the beginning of the Six Nations."
"It is a tough competition to win or finish second (in) and we are pleased with where we are at the moment," said Gatland.
(Writing by Julien Pretot; Editing by Neville Dalton)
