I transcribe a lot of music. The output is usually lead sheets or bass parts (exact transcriptions). I notate all details that seem essential to a song and chord symbols are always correct (though I might decide to simplify them).
I begin by adding markers in Reaper for each bar/measure. I'll later rename and colour-code some of the markers to identify sections. I use several plug-ins: a tool to isolate left, right, mid or side; EQ to try to isolate parts; a frequency analyzer to see what's going on if my ears need help. Occasionally I'll open something up in Melodyne. I've moved from Sibelius to Dorico for the notation.
In theory deCoda should be able to do a lot of the work.
It opens files and analyses them very quickly.
It does a reasonable job of identifying and naming sections. Unfortunately the developers have chosen to call these "parts" (Part A, Part B, Part B2 etc.). Given that I'd be thinking in terms of bass parts, guitar parts etc., this is annoying and I hope the terminology will be changed as soon as possible.
deCoda does a good job of putting simple songs into bars/measures. It can't identify rubato and tempo variations automatically. I'm not going to be commenting on the editing tools in this quick review.
The chord symbols are very often wrong, the harmonic analysis isn't thorough (don't expect much beyond major or minor even if that means the results will be wrong), and there's nothing to indicate the bass notes (no slashes to indicate inversions or pedals for example).
A frequency band and area of the stereo field can be isolated graphically (as one would in Roland's R-MIX) but unless I'm missing something, there's no way to make more than one selection. One can choose to isolate or exclude the selection. I imagine the tools will become more sophisticated over time.
deCoda's Melodyne-style piano roll analysis is pretty good though I found that harmonics were sometimes indistinguisable from fundamentals (particularly in the case of bass lines). There's no way to delete audio material as one can in Melodyne. One can draw synthesized notes on top of the audio (and export the results) but in 1.0.1 I've found the drawing to be too buggy to be usable.
Slowing the music down is simple and the pitch handling is exemplary as one would expect from zplane.
Navigation through a song is easy enough as long as one learns the keyboard shortcuts.
deCoda is interesting as essentially it offers all the right analytical tools. Whether or not I'll actually use it at all until it's much more developed, is another matter. As it's so quick I might use the piano roll occasionally. Though it's being marketed as a tool to "help you learn songs", I can't see it being much use to beginners until the harmonic analysis at least is improved.