While I don't know anything about the specific lens you refer to, provided it mounts properly using the adapter, it should function fine in manual and Av modes. Olympus mounts appear to have a longer flange distance than the Canon EF mount, which means that your adapter does not need to have any extra glass. This is good as extra glass can affect image quality.
What you won't get with the lens is the ability to shoot in Tv, P or full auto modes (or any of the "creative" modes). You won't have autofocus either.
In addition, because you have to stop the lens down manually using the aperture ring, focusing can be a pain if the light isn't great, since stopping down the aperture will cut the amount of light entering the viewfinder. You might also have to use stop-down metering to get your exposure right.
Having said all that, I use an old Nikon-mount Sigma with my 30D, in low light, to do macro photography and often get great results. See below for an example of what can be done with fully manual lenses.
Finally, an OM to EF adapter seems to cost in the region of $10-$15 on EBay. I'd say it's definitely worth a punt at that price!