I am trying this week to use L4 in serious way for work. Here are some impressions on using it fwiw.
Note that while I am by nature the person in the paper signed "disgruntled in Ireland", some of this is actually positive 
L4 - sugar and spice
My o my but print looks good in L4
Interlinear "window" very helpful
Passage guide customising - very good
Can put buttons on toolbar 
Speed is ok on my comp. Wait for long and complex searches, but no noticeable wait for basic stuff.
"Rate this commentary on passage" in passage guide - v cool
Notes text formatting - great... Can you change the default text?
New tab/parallel resources - I like this, takes a little while to populate though.
Command/search bar good and impressive results.. Though I don't enjoy remembering and typing command style things - rather click a button 
Music Media and Maps - lots of improvements 
Clippings as a sermons and talks ahead planning tool - nice.
Visual filters - I like link to open panels lots - open the right panels and everything lights up!
L4 - worms and snails
Grey n white - e.g. there are stars on passage guide against commentaries (mark this article esp. helpful) on my screen did not even see them at first. Grey on grey for window titles, and tiny little + signs; is there a way to personalise the "colour" scheme?
I have got the notes skip out to "view only" bug - its like a game... Which key will make it happen this time?
Buttons added to toolbar are green and similar - not distinctive enough
The printing thing again...
When wishing to add a note from right-click, there is no option to create a new note
Handouts - oh all the wrong stuff already added...
Music - more n more please
Trying to use clippings as verse lists - not so much.
L4 - puppy dogs tails?
Add Name and details to a passage guide... And notes for each section of the passage guide...Ooo what's that for?
Yet with notes you can add title, but no details panel - can we have title and details for notes?
Handouts - sorry but I don't get this one. Mic publisher, Word, etc need not fear the competition, so why not simply go for really cool export to dedicated programs instead
Nice selectable list of resources to use and "export to" button?
Anyway, that's it for now.