I've used agent mode, but I tell it not to go hog wild and to not do anything other than what I have instructed it to do. Also, sometimes I will tell it not to change the code, and to go over its changes with me first, before I tell it that it can make the changes.

I feel the same way as you in general -- I don't trust it to go and just make changes all over the codebase. I've seen it do some really dumb stuff before because it doesn't really understand the context properly.