The Belgium international has struck seven times in 10 league matches and scored two in last weekend's thrilling 3-3 Merseyside derby.
Lukaku, on loan from Chelsea, had been relatively quiet up to the point where he got Everton back in the match with his first in the 72nd minute, but Martinez said he was happier with the big striker's overall contribution.
"It was great to see him scoring goals but I was more pleased with the manner he worked hard for the team," said the Toffees boss.
"He was a real trigger for us in the way we stopped Liverpool from playing and he deserves huge credit for that.
"He is developing strong relationships with players and you can see Romelu is growing as a footballer week by week.
"If he scores goals everyone can be happy but I measure his performance a bit further than on scoring or not scoring.
"He is such an intelligent person, he always knows how to behave in every single situation and, yes, he needs to score goals but he has been very level-headed in every single situation he has had at the club."
Lukaku's form has ensured fellow forward Nikica Jelavic, who has scored one league goal since December 9, has been restricted to a bit-part player.
The Croatia international also seems to have been overtaken in the pecking order by on-loan Barcelona youngster Gerard Deulofeu and that seems to have raised questions about the 28-year-old's immediate future.
With his country heading for the World Cup finals in Brazil next summer, Jelavic knows he has to play regularly to remain in contention and speculation has suggested he would look for a way out of Goodison Park in January.
"It (speculation) doesn't surprise me because obviously Nikica Jelavic is a terrific player to have, he's a goalscorer and you don't get them easily in the game," said Martinez.
"Because Croatia have qualified for the World Cup you can imagine he wants to be fresh and ready for it.
"From our point of view it is very important he stays with us and he needs to be ready to help the team when the opportunity arises, which could be very soon."
Martinez insists he will, if necessary, only add to his squad when the transfer window opens with midfielder Darron Gibson and striker Arouna Kone (both knee) sidelined by long-term injuries while left-back Leighton Baines could be out until the new year with a broken bone in his foot.
"We want to add if the right player and the right character becomes available but it's not a real need," added the Spaniard.
"What is important is that after the transfer window we are again stronger than when it opens and that will always be our focus."
Everton face Stoke at Goodison on Saturday looking for a return to winning ways after three successive draws.
Like the Toffees, the Potters, also unbeaten in three games, are undergoing change with a new manager this season but after a slow start Mark Hughes' methods appear to be taking effect.
"I think Stoke are starting to show they are very good, when you have been unbeaten for the time they have it shows they are clicking together," said Martinez.
"I think they have kept things that the team was good at in previous seasons and that makes them a strong side who can hurt you in many different ways.
"I don't think they have lost anything (in changing their style), they have added and are trying to be a bit more expansive and controlling games a bit more.
"Only time will tell but I do feel they have not made a radical change, they have adapted to a new style and whenever you face Stoke you are going to be in for a big game.
"We only added one point against Liverpool and we need to keep adding points on a consistent basis.
"We are looking forward to turning those draws into three points and making sure we become stronger as the season goes on."
Source: PA
Source: PA