My opinion: Terry Semel didn't get the job done he said he would. Admittedly, I'm biased; he insisted that Y! buy Overture (which had bought AltaVista), and laid me off as well as several other people I know. But even if I hadn't been affected, I would still be critical of his tenure at Y! He neither was able to monetize Y!'s content, nor was he able to build a search platform that took market share away from Google. Even if Panama (the new sponsored search platform) is a technical success, it must be considered a business failure because it took too long to build, and thus did not provide the income boost that Semel said it would on the investors' time schedule.
It would not surprise me at all if Y!'s future looks like this. Current and former AVers will recognize the signs all too well. Folks who are laid off will be bitter; folks who aren't will be stuck with cleaning up the mess. As much as I complain about not having a job, I wouldn't want to go through the pain of trying to patch together a "troubled company" just to see it get sold and wind up being laid off anyway (unless they paid me a lot of money).