Virtually none of the large, professionally designed sites use frames. In some instances, a site designer would be better off using frames, especially for large, highly organized lists. But in most cases, frames are more of a convenience for the designer and not visitors. Framed search engine entry pages cannot possibly receive as many visitors as properly designed non-framed content pages. This is particularly true for larger sites with varied content.
Entry pages for all the possible keywords are simply more work than using unframed pages.
Yes, there have been lawsuits over frames. Some companies have lost money over their use of frames. In conclusion, I'd say there are only a few instances where the use of frames would be appropriate. We formerly used frames, but not anymore. We have also redesigned most of our older client's sites which used frames.