They ended their campaign on a winning note with a record 51-3 win over Scotland with No.8 Faletau touching down one of six tries scored by Warren Gatland's troops.
However the 23-year-old couldn't shrug the feeling that better performances against Ireland and England might have put them in contention to retain their RBS 6 Nations title.
"The win is bittersweet, I guess," said Faletau, who has been nominated for the RBS Player of the Championship.
"We're frustrated and we've got regrets about the way we played in Ireland and England. Scotland were a bit more vulnerable when they got the red card and we managed to get a few points on the board.
"We were good in patches but we could have been more clinical, which is something we need to work on.
"Overall we've got to be disappointed with how the tournament has gone for us. We wanted to win the Championship but it didn't quite happen for us."