Though Giggs became well acquainted with van Persie’s fearsome goalscoring ability during the striker’s spell at Arsenal, his appreciation of him has since grown.
"I don't know if he has exceeded expectations because we all knew what he was capable of," Giggs told PA Sport. "But sometimes you don't realise just by playing against them how good they actually are.
"When you train with them every day and play with them every week it is different. That has definitely been the case with Robin. We knew about his goalscoring but it is his all-round play. He is a brilliant player – long may that continue."
Sir Alex has insisted he’s "not bothered" about the potentially hostile reception van Persie will receive on his return to Arsenal, for whom he scored 132 goals in eight seasons.
Giggs believes there will be no problem on the pitch and hopes the frontman gets some recognition from the Emirates Stadium fans.
"I think the players will give Robin the respect he deserves," the Welshman added. "You might get certain fans who are not happy because he was their best player and he scored so many goals for them. You are going to be disappointed as a fan when someone like that leaves your club.
"We are happy he came to us and has had such a tremendous season. Hopefully the fans will give him the respect he deserves but you can't always guarantee that with fans because he was such a good player."
More: Robin's respect for Ryan | No.20 fires Reds to 20 | RvP greedy