I saw the original but missed the remake, which was frustrating, because I wanted to compare the two.
I'll tell you this much. The original was shot for something like $350,000, which wouldn't even cover the makeup budget of the remake; they didn't even have the money to make a special effect 'saw, so what you see for the entire film is a live and working chainsaw. Gunnar Hansen, who plays Leatherface, says the 'saw started up every time, and that sometimes he would work the saw just three inches from the actor's face, looking through the tiny eyeholes of his Leatherface mask.
There was in fact one scene where he goes beserk with the 'saw (you see it in the film), and he could see through his tiny eyeholes the director of photography, one of the producers, and director Tobe Hooper running for their lives.
One of my favorite stories that Hansen tells is of one of the characters who took ten hours to put his makeup on. After that ordeal he announced that he wasn't going to do that again, so he wanted all his scenes shot NOW, and then he's leaving for good.
So they shot round the clock for 27 hours to finish all his scenes, the most extensive of which was a dinner party in an enclosed room with an average temperature of 100 degrees inside.
Everyone was broiling, literally, from the Texas heat, had gone without sleep for more than a day, and were under enormous pressure to finish the scene, which was experiencing plenty of trouble, technical and otherwise.
Gunnar Hansen confessed that several times he lost it. When someone yelled at him to "Kill the bitch (actress Marilyn Burns)," Hansen, thinking by this time that he really WAS Leatherface, stood up and walked over, ready to really kill her.
Later in the same scene, Burns' finger was to be cut by a knife. Hansen held a knife with its edge taped for safety, and a tube on the hidden side ready to spout blood...only the fake blood had congealed, and the tube wouldn't spout.
After the umpteenth take with the blood not spouting, Hansen turned around, took the tape off, and on cue, actually sliced Burns' finger open. Burns' horrific reaction to Hansen's cut, that wasn't acting.
Really, there's an energy and force and--well, I hesitate to call it realism--to the original Texas Chainsaw that, I don't think the remake is going to match.