Except for the general tendency to describe brief glimpses of tentacle-like structures and glistening gelatinous masses. grin But yes, much of Lovecraft’s strength comes from the idea that we (the reader) are given to imagine the creatures he presents out of whole cloth.
With this in mind, could a good film be made of Lovecraft’s work? Yes, but the filmmakers and producers of the film would have to keep in mind the lessons learned from The Blair Witch Project – that less is more, and that the audience is often most frightened by what they don’t see. Given the procilivity of the modern horror film to show almost every last detail of the latex wonders they create for the screen, this would be a fairly major paradigm shift, and would go against the instincts of many creators in the industry today.
It could be done, but it’s not bloody likely.
Perhaps the most stylistically Lovecraftian film I know of is one that relates almost not at all to Lovecraft’s work: Adrian Lyne’s Jacob’s Ladder, which in its most horrific moments shows the audience only enough to make them ask “What the Fuck was THAT?!” but never really gives us a chance to identify what we’ve just seen. It’s a fine line to travel upon, but Jacob’s Ladder is masterful in that regard. A film made in that style, based on a fairly faithful interpretation of a Lovecraft story, would be a very effective interpretation, to my mind.
Jeepers Creepers was also surprisingly effective in this regard (yes, the title is dumb, but the film is better than the title leads one to believe), and parts of Carpenter’s In the Mouth of Madness also work the subtlety factor well, though other parts simply ruin the film. Even Clive Barker’s original Hellraiser uses some remarkably subtle techniques early on, but again, somewhat ruins the effect in the end (and the later sequels aren’t even worth discussing).
Of course, I’m a little biased. I’ve been slowly working on my own script version of The Case of Charles Dexter Ward, maintaining a close interpretation of the story while making it a little more interesting to a modern audience (stronger, more developed characters, mainly). If it ever gets made, I think it could be very good. Also, as someone else mentioned, At the Mountains of Madness could make an excellent film, if done carefully. That one is also churning in my gears.