Clementine: A triumph of Free Software

Ages ago, in the long-forgotten days of 2008, there was Amarok 1.4. And it was good. Then KDE4 came along and Amarok was rewritten, reshaped, becoming something... different. Something unsettling. Something not altogether pleasant.
Fear not. Today we have Clementine.

I consider Clementine a triumph of Free Software. A great project fell off the rails, so someone else picked up the pieces, forked it and kept the spirit alive.

Features present

Clementine embodies everything good about Amarok 1.4, in a shiny Qt4 package. The layout is eminently pleasant to use. It uses the classic "spreadsheet" playlist view that saw so much success in Amarok 1.4. If you care about cramming as much information about your music as possible onto the screen, this is as good as it gets. It's boring, and that's a good thing. It gets the job done.
Like Amaork, 1.4, in Clementine you can very quickly drill into your music collection, filter it, view recently added tracks, group songs by artist or album or year or genre or a combination of those things. Clementine also handles all of the edge cases correctly: it lists albums with Various Artists exactly how I'd want (exactly like Amarok 1.4). It correctly handles songs with non-Latin tag text.
Clementine detects additions and changes to my music collection instantly, without the massive scan-lags on startup that plague some other music players. Clementine doesn't bat an eye at my 7,000 song collection. There's no MySQL integration, but I don't need it. Clementine's SQLite backend supposedly handles 300k songs without much problem, which is good enough for me.
Clementine has Last.FM integration. It has three different styles of desktop notification. It has visualizations. It handles USB devices. It understands reply gain. It has cross-fading. It has an equalizer. It has a transcoder. It has a cover manager.
I'm tired of listing features. Let's just say it has every useful feature you'd ever want. And if you don't need a feature, it stays out of your way.
And for a program under such active development, it's rock solid. I have yet to see a crash. And speaking of active development, if you follow the activity in Clementine's SVN repo, you will find that this program is updated almost daily. How the devs find the time, I don't know, but I'm grateful. This program has gone from non-existent to awesome in record time.
Clementine can use gstreamer, so it even works cross-platform. I fired it up on Windows 7 the other day and I was amazed at how good it looked and felt. It supposedly also works on OS X.
Clementine doesn't cook your breakfast for you, but that might be in the works.

How to make a good UI

A perfect example of the polish of Clementine's UI: Tagging. How do you tag a whole album worth of music at once? You can select some songs and right click and go into a dialog, like most music players allow.
Or:

1. Edit a tag for a single song (inline) by clicking the field. Let's say you edit Artist.
2. Select multiple songs in your playlist. (Click and drag, CTRL-click, Shift-click, CTRL-A, whatever.)
3. Right click the Artist tag in the song you edited, select Set Artist to "XXXXX", and now all the songs you selected will be updated.

This is the kind of UI innovation that I like. It's simple, it's useful, and it's predictable. You can get things done without going through dialog windows, without a million clicks, without spending a minute scratching your head figuring things out.
(Meanwhile Amarok 2 is busy getting rid of the Stop button and making the volume control circular.)

Features missing

Admittedly, Clementine is missing a couple of features I wouldn't mind having. You can't skin or theme Clementine. You can't rate songs. You can't display song lyrics. You can't "queue" songs. But oh well. I can live without these features because the rest of the program is so darned good. For all I know, these features might pop up next week. I wouldn't be surprised.
The Clementine devs seem to be very friendly and responsive to feature requests and feedback, which is also great.
Clementine is also missing a few features/bloat that I'm glad to see NOT ported from Amarok. Wikipedia integration? Good riddance.

I would pay money for this program.

In November 2009 I had this to say:

(Anyone out there reading this, if you port Amarok 1.4 to Qt4 intact, I will pay you. Seriously. I will pay you money.)

The offer still stands. I will pay money for Clementine. I'm still waiting for a Donate link so I can do so. (Clementine devs, are you reading this?)
Why do I care about this so much? Because I have music playing whenever I'm using this computer, and when you add up work plus free time, I'm at this computer 8-10 hours per day. Music keeps me sane during multi-hour debug sessions. Music is an integral part of my life, and a music app is an integral part of playing music.
It's very important to me that the programs and tools I use all day are comfortable. Otherwise I become cranky. If you were a carpenter, would you want to use a hammer with a wobbly handle all day? I'm a programmer, and I want to use comfortable computer programs.
Clementine is very comfortable.