At the conferences a lot of speakers talk about using MindMap in testing. So I tried to use it in my work.
Shortly – I didn't like it (or didn't understand). I guess it is useful for describing some system and relations in it system, but I don't understand why testers should do that – usually analysts describe relations. Of course, there are projects with poor analysis where testers should do some extra work to understand the whole system or to explain it to someone else, but it is not testing – it's tester doing analyst's job. So I can't say, that MindMap is a testing tool.
One more purpose of MindMap, that I heard about – is writing notes during exploratory testing session. In that case I don't understand why you should connect these notes with each other? I use simple checklist for that purpose: before (and during) test session write down chapters that I need to check; during the session under these chapters write bugs or functionalities that need to be clarified; after session read the list, report or clarify the problems and strike out the lines. Lists are more readable (in MindMap there is no start and end), lists suits more for screens and papers (MindMap can very easily go beyond the screen or, worst, beyond the paper, checklist can be just continued on second page), in lists it is more convenient to strike the line out, when it's done.
There is one more usage of MindMap, which is not connected to testing – note-taking during the lecture, tutorial or conference. Again, don't understand why you need connections in these notes – usually I write down a thought or an idea, that need to be processed later. So after conference I need to read all notes and do something about them – checklist is more convenient for that purpose.
I agree, that in some cases (mostly for analysts) MindMap is pretty useful tool, but I think that it is overrated in testing world.