This is going to be a long one. I thought I would share some thoughts and reactions to version 4 while it is fresh in my mind. I was a frustrated beta tester and not happy with the new stuff.
I jumped in on the beta testing when it was offered. I was put in the DVD install group but also took advantage of the download for us impatient types. Unfortunately, several things stopped me from fully participating in the testing. First, I'm an IT drone these days and our end-of-year processing coincided with the beta period. I spent most of that time keeping the company servers up with prayer, chewing gum and a patch or two. As a result, I didn't have much time to test and I didn't show my face much (at all, really) on the beta forum.
Second, the installs I did perform were more or less flawless. I installed on my home machine (vista 64) with the DVD, and on my several laptop partitions (Vista 64, Win7 64-bit RTM, Win7 32-bit RTM) by both DVD and download. Installs, downloads, updates, indexing, etc. went eerily smooth. Nothing to complain about there.
Third, the few bugs I did find were never around long enough for me to reproduce and document. A couple of times I found something that would crash the app but when I restarted, Logos jumped right into an update, and when it was finished I couldn't reproduce it. I put that down to dedicated and manic testers and highly-caffeinated Logos developers. I also found a few odds-and-ends artifacts in the GUI (for popups or rendering and such) that could only be reproduced on a hit-or-miss basis, and as with the crashes, an update would drop and then I couldn't reproduce at all. The speed of the testing and respin cycle during the beta was nothing short of amazing.
The last reason I didn't get too much involved was that, at first, (here it comes) I hated! hated! hated! the new interface and underlying philosophy of the new design. I had learned how to get v3 to do what I wanted. I had collections, searches, workspaces, resource associations, menus and the like all worked out to help me study the way I studied best, and those were all gone.
I couldn't make v4 do anything the way I wanted. My initial frustration level just with dynamic collections almost did me in. I just wasn't grasping how to get useful search terms and the collections I was making were uber-messy with too many false hits. I was ready to plan a memorial service for my library because I couldn't see any way to make this new stuff useful to me. As I said, I'm in IT. I've lost count of how many times I've had to learn new tools or a newer way of doing things but I just wasn't getting any good feelings here. With all that said....
I gave v4 another try last week when it was released. After a couple of days, I started to think it wasn't so bad, that I could at least live with the new stuff. Lots of good pointers on the forums helped me along, and sometimes a liberal application of the cluebat helps too.
For further motivation, the Gold to Platinum upgrade gave me several new resources I'd been itching for and the good pricing just pushed me right along. A pox on the House of Logos for tempting me with great collections at screaming prices! Please keep it up.... 
My wife and I spent this last weekend in a creekside cabin in Sedona, AZ for a weekend getaway. She brought several books and a journal, while I resolved to bring nothing but my Bible and laptop. I was going to get to know v4 and give it a chance to shine, even if it killed me.
Long story short -- I'm a convert.
The word 'paradigm' is one of those overused corporate buzzwords that make me shudder. The move from v3 to v4 really does require a paradigm shift. It can be painful, but in this case, very much worth the effort.
Dynamic Collections and Collections of Collections: Once I figured out what it was driving at, so cool!! I started creating collections of Bibles, commentaries, and so forth, and it all started working the way it should. When I got to collections for my favorite authors, I then wanted an All Favorite Authors collection. It took me a while before I figured out where to get current collections from in order to drag them to the Plus field. I haven't played much with Ratings or mytag yet but I get it now.
I love the user history. It makes it so easy to backtrack to what I really need after I've gone down a rabbit-trail.
Favorites Tab -- love it.
Search speed is amazing. It is so fast that when I first saw it, I thought the search engine itself was crashing out.
Layouts - also a very nice touch. An excellent replacement for workspaces. The layout history is very handy.
Customizable guides look very nice. I’ve been following the forums discussions on them and am looking forward to the improvements.
I'm glad that the Ctl-F quickfind is still there.
I'm still figuring out how things fit together in the big picture. It appears that search terms, keywords and syntax have undergone some changes and I'll have to relearn some stuff.
I'm glad that the full-page reverse interlinear style is coming back. My greek kung fu is not the best (two years of it too long ago) and I find the ribbon confusing.
The learning curve on L4 is steep but not nearly as tall as it was in v3. Much of what I want to do is more intuitive than before.
Speaking as an obsessed layman rather than a professional scholar, teacher or pastor, bigger and faster searches that yield more results are great. I remember the bad old days of library research, where one could spend days in the stacks with a sockful of nickels for the copier, a highlighter, a fistful of notecards and writer’s cramp. Now the challenge is to pare the gargantuan amount of data down to a usable level. There are times when doing a quick lookup in a handful of trusted resources is preferred. Associations were an easy way to get control of the huge number of resources available. Perhaps the new system already allows this but I’m still learning the nooks and crannies.
Overall, a very impressive effort.
Larry