I have loved using Logos for research purposes for sermons, papers, etc. I like the ability to copy and paste something right into my document (or now, even use the clippings feature instead of having a notes document in Word). My only complaint has been the citations feature. It seems to have such promise--eliminating the tedious work of trying to properly cite a quote, but at least in my experience (in L4 and L3), it falls far short of that. My citations are often filled with some extraneous bits of information. That's not usually a huge deal, because it's pretty simple to delete what I don't need. I'd rather err on the side of too much information than too little. One of my biggest disappointments is the lack of page numbers. I have my citation style set to Turabian, and whenever I copy and paste something, the footnote I get is similar to what would be in a bibliography--namely a citation of the resource not the citation of that particular quote.
I hope I'm being clear. This is feature that would save students (and pastors who care about correctly citing sources) incredible amounts of time, but it can actually be slower than doing a citation from a print source (since you have to turn on the visual filter for page numbers, locate your quote, possibly find the author of the section of the book you are reading--as opposed to the author of the entire volume, which is what Logos gives--and sometimes locate things like volume numbers.) I realize that some of these things would be difficult to automate, but I would love it if the automatic citations could be a little bit more intelligent. As it stands now, I still have to manually cite everything in order to make it correct.
If I'm missing something here (a distinct possibility!), please let me know!