I'm looking at frames from two points of views here: screen resolution and people who browse Web Programming site using speech software.
One common complaint that people have against sites using frames is usually that webmasters tend to forget that visitors don't have the same large screen resolution that the designers have when they created the web page. Sites with frames tend to provide a smaller area for people to view the main content of the site, since the outer frames occupy some of the screen real estate as well. If the web designer has not checked his site using a lower screen resolution like 800x600 and 640x468, and tested its usability with those lower resolutions, he may not be aware that the site is difficult to use in such situations. Visitors may have to scroll horizontally and vertically continually just to read the content. The situation is worse if the designer removed the scroll bar (because it looked fine without it on his high resolution screen), and visitors find they can no longer scroll left/right/up/down to read the content.
If you use frames on your site - be sure to check how it appears under lower resolutions. By "check", I don't mean to see if your site still looks pretty. Try reading all the content on your site with those resolutions. If you find that the site is inconvenient to use under those resolutions, you may need to rethink your design. Remember, your visitors don't have the same amount of patience with your site that you have.
Framed pages also pose certain difficulties for people who have to use speech software to access your pages, such as the visually impaired. Unlike people using a visual web browser, the speech software reads every item on your pages and frames serially. The person using such software does not have to ability to skip portions of the page because it appears irrelevant. Neither is he able to match what is displayed on one frame with the content appearing in another. Remember - matching the content of one frame with another requires ability to see the layout.
I'm not saying that this necessarily precludes the use of frames on your site. What is needed, instead, if you think you really need to use frames on your site, is to plan carefully so that both the user with a low screen resolution and the person using speech software are able to access your site as you intend.