Argento has been at the helm of many giallo films, but Deep Red is undoubtedly his best. He helped popularise it with The Bird With the Crystal Plumage, added more of his personal flourishes with Four Flies but, with Deep Red, he truly perfected it. Not only is it Argento's bet giallo, it could be the greatest giallo, period. It is a labyrinth of a film, with many twists and turns. As usual, Argento's camera is star of the show, and here it barely stops moving. It makes the whole experience undeniably suspenseful and, yes, there are lashings of visceral violence in there, too. Goblin's score is one of the strongest of their collaborations with Argento and you might be surprised to see some allusions to high art (look at for the ode to Edward Hopper's Nighthawks). Multiple versions of the film exist, although thankfully the fully uncut 126 minute version is widely available in a remastered/high definition form. A 3D remake (with George Romero directing) was talked about several years ago but mercifully never came to fruition.
