I use a Hoya RM 72 on a Canon 10D for infrared, and it works with some limitations. I often get weird kinds of lens flare, even when using a lens hood and not pointing near the sun. I've used it with the 28mm f2.8, 35mm f2, and 50mm f1.8 lenses, and they all flare. Composition is hard because the filter is nearly opaque to visible light. It must be removed from the lens, the scene composed with the camera on a tripod, the filter replaced, focus adjusted to compensate for infrared, and the picture taken. Exposures are long, typically 15-30 seconds at f8-f11 under strong sunlight. The results are somewhat soft, though not nearly as ugly looking as most black and white IR film I have used, which have awful grain. At modest sizes and with strong sharpening, the pictures look good. Foliage is white, skies are very dark, puffy clouds stand out. The color is nearly monochrome, pinkish gray, so I just convert to grayscale to print.
The RM72 is the cheaper of Hoya's two IR filters. The other one (RM 90) goes much deeper into the IR spectrum, or you can think of it as cutting much mroe visible light. The RM 90 is fantastically expensive, and I have no experience with it. The numbers indicate where the filter passes the most light. 72 means 720 nm, just slightly beyond what is thought of as the red end of the visible spectrum (400-700nm). The RM 90 passes the most light at 900 nm, much further from visible light.