Does this help? https://plus.google.com/115071343963809487647/posts/ftmCbLfuK1r

or this?
http://www.softpedia.com/get/Multimedia/Audio/Other-AUDIO-Tools/Winamp-Playlist-Creator.shtml

Hmmm. Kind of. The tool seems to be just creating .m3u playlist files in the WMP directory. But I can do that with winamp, playlist export. I get the feeling music manager should probably just find playlist files in directories but I haven't proved that yet. That would avoid going anywhere near WMP.

ps. Really hate youtube tutorials. Why can't I just have a text blog!
ps2. Music Manager doesn;t seem to be able to do much intelligent matching, instead uploading the whole of every track. Maybe that's my obscure taste in 5 minutes old music getting the better of me!

I agree about youtube tutorials, especially for what should be straightforward things. Also, I thought Music Manager always uploaded the whole tracks.

It's all turning out fairly ugly. Winamp playlist export, itunes playlist import (which takes forever), and then Google Music Manager upload from itunes, choose the playlist, which also takes forever.

.m3u is a fairly widely supported format understood by pretty much everything. Music Manager should just support it directly. 

Try this maybe? https://github.com/simon-weber/Google-Music-Playlist-Importer

Everything I read says it is possible, but I can't seem to find a way either (apart from perhaps the home-made script above). I find Google Music has clearly imported some of the playlists I had when I first started the service, but I'm not sure how/when or where they are on disk now. I've just exported another playlist from Clementine, put it in my Music library on disk, and started Music Manager. Waiting... waiting... waiting. Nothing so far.

I've just gone off searching for a google groups to discuss the problem with Googlers who might be interested. No luck so far, Discussion about music manager seems to happen in Google Apps which doesn't seem right. 

I'd be interested to know if you can find a way. I'm stymied myself now. The playlists Music Manager synced originally have disappeared from disk somehow ...... really odd. The new one hasn't been synced yet either.

If I discover anything, I'll report back here. At the moment, I've successfully exported a playlist, imported into iTunes, uploaded tracks that were found in that. But the playlist itself didn't make it to Google Play.

So it was exceedingly slow, but winamp export playlist, itunes import playlist, restart music manager and change source to itunes does seem to eventually work. All the tracks and the playlists have appeared in Google Music. However, my largest playlist says 1000 tracks while it's 5150 in both winamp and itunes[1].

I'm rapidly reaching the conclusion that Music is yet another Google work in progress. It may eventually be ok and usable, but right now there's too many gotchas and unfinished or missing function.

[1]Looking at the tracks, I think 1000 is a playlist limitation. It's just chopped the list round about "D" in artist order.

Thanks for checking all of these playlist issues with Google Play Music. I personally cannot believe how it was possible that Google devs ignored standard music playlists in an otherwise pretty cool music player and site.

When I copied my old phone collection to a new Nexus 4 and pointed Google Play Music to it, it imported the .m3u files in there, but unfortunately they are out of order, in the sense that some songs, or even whole tandas, get in the wrong place. Seems random, but it is reproducibly random (if I erase the app memory the wrong lists show the same wrongness).

This is very unfortunate because I use the phone for milonga DJing, and order of songs, tandas and cortinas is crucial. I have several years of different performances (each a .m3u list) and it is crazy that I can't import them or export them from the phone.

Also, the ones I put in the device don't appear in browser google play music. but the browser ones are shown in the device...

Lots of brokenness, I guess I'll have to find a different player for the phone. Google is doing more and more evil in the last years, I guess we need to get used to it.

Any updates or progress here? I too want to import play lists. I refuse to load iTunes on my pc

https://github.com/soulfx/gmusic-playlist has some scripts that can be used to import and export playlists.  I used the import script to import playlists and favorites from various streaming music services I've used over the years.

That's a start. Really needs to support the common playlist file formats though rather than inventing a new one.

I was looking today at GPM and wondering how to download playlists you create online. I can't see any way of doing it in the desktop web interface though the help suggests it may be possible in Android. You can download a whole album, but not an artist or playlist.

And a year later from this post, there's still no way to upload a playlist. The new web interfaces for uploading don't recognise .pls or .m3u. And Music Manager still doesn't.

I finally canned spotify when songs would mysteriously change from one album to another, getting a slightly different master or remix etc., and decided to check Apple Music. No, way.

Enter GPM - perfect - it lets me untether from my FLAC external HDD when I'm mobile with my laptop, but I was shocked to see it doesn't handle .m3u playlists. 

"I'm rapidly reaching the conclusion that Music is yet another Google work in progress. It may eventually be ok and usable, but right now there's too many gotchas and unfinished or missing function"

^ sad that this was posted 2 and half years ago and looks to be largely true now.

BTW, had this problem (searching M3U supported app) found this, and it has worked like a charm

Rocket Player
https://play.google.com/store/apps/details?id=com.jrtstudio.AnotherMusicPlayer

+Heikki Kaperi Looks good but how would this help with the OP? "copying playlists from Winamp to GPM"

Hhh, tried couple of things. didn't get it to "easilly" carry over to GPM. Guess I'm just saying that if you can live without GPM, this is a good music player, that supports M3U

(then, I know that this won't help much, but a interesting related info. I had Galaxy note 2. In it, Samsungs music player supported M3U nicely. My files where in SD card. Just upgraded to Moto G 2015 2gb, and GPM had my playlist that was only used in Samsung player (never used GMP). Then when I upgraded my playlist with new songs, and paste'd new M3U files, I was supriced that GMP playlists didn't upgrade according to those files, like Samsungs music player did. So, I just replaced GMP with Rocket player, because it supported M3U files (and was well made))