Do you find a computer-assisted qualitative data analysis tool useful?
My answer might not be as useful to you because it only deals with my personal experience. I often deal with mixed methods work and qualitative data analysis is something I do about ~25% of my time.

I have used Atlas.ti because it is provided free on my school server. However, realistically, I used Excel to code themes, categories etc. following a grounded theory approach (Glaser and Strauss, 1967). I don't find much use for it but I know significant numbers of professors and graduate students who swear by it. It seems to be the SPSS of the qualitative world.

One powerful use of Atlas.ti that I can attest to is organization, search and visualization of categories, codes, themes and performing some simple reliability measures (Cronbach, Krippendorf) etc. 

However, the same can also be done in Excel with some elbow grease. :)