iTunes' package comes in a 19 MB file, and includes QuickTime Player 6.4 in it, and also some CD burning add-ons/drivers. Installation is very easy and it requires a reboot for the CD burning software to be initialized.
Upon loading the application for the first time, it scans your "My Music" folder for songs and other media files. They are automatically added to your Library in the iTunes database. Double clicking the songs will start them playing and quality and multitasking with the system is excellent (I get no drops of sound when doing other processor-intensive work).
I like the Radio collection that iTunes is fetches from the web, as I am an avid listener of Di.Fm/Eurodance and while the first time iTunes could not find any radio stations, the second try found them all and fetched their streams with no problems at all. However, I found that that iTunes "loses" the stream on the 128kbit versions and it needs to rebuffer every 4-5 minutes (setting buffer size to "high" doesn't help). I don't have such a problem with my WinAMP usually. The 56k streams work fine with no gaps.
The Music store is there, same as in the Mac version of iTunes. You can shop either with a shopping cart or via the "one click buy" feature.
I liked how iTunes automatically found some songs on my library, e.g. The Sound Of Silence by Simon & Garfunkel and placed it seperately on a special folder "60's music," presumably to demonstrate the categorization features. The Visual Effects on iTunes are also very nice, but I am not yet sure if there is a way to add new effects and plug-ins to it as you can for other media players.
Importing songs from CDs works like a charm, and you have the choice of using mp3, AAC, WAV or AIFF as the encoding format, but I can't test burning yet as I haven't found the time to install my new Memorex combo drive on this machine yet. You can also share music within the same network, but I saw nothing about Rendezvous (possibly requires OS support). Other features include de-authorizing computers from using your shared music, checking the status of purchased music, fetching artwork from the music you currently listen, and opening other streams.
So far, so good. I found no glitches with the application or its stability. Except one thing: its UI speed. For the life of me, I am almost unable to resize the iTunes window (with visual effects OFF no less)! Its window UI is almost unresponsive. Menus and native-windows-looking alerts are responsive and fast, however the metal interface is just unusable here. I can't easily resize the application, and with difficulty I can scroll the scrollbars in the store or the Library! After many attempts, I managed to get the window size down to about 640x480 and then the application did become more responsive and workable. But on a normal ~1024x1000 window, it is just unusable. There are times I can't even move the whole window across the screen! Note: I am not talking about playback (which works fine with no performance issues), or when in mini-mode: I am talking about scrolling/resizing the app when the window is in normal mode and bigger than 800x600. Resizing the window when in "Music Store" is almost impossible here! Update: Upgrading to the latest graphics drivers didn't help.
This machine is a dual Celeron 2x533 Mhz with WinXP PRO (Apple recommends a single 500 Mhz Pentium-class CPU as minimum), and I swear, this is the slowest application I have ever run on this machine. Ever. Even some big java apps I ran in the past were not that bad. I also have here a Cube G4 450 Mhz machine, and iTunes on OSX "flies" compared to the Windows version. Well, it doesn't actually fly either, but it is absolutely usable and responsive enough to do the job. On my WinXP PRO, the speed is just not acceptable.
I like iTunes for Windows (especially when used in the mini-windows-mode where doesn't take much space). However, its overall UI speed needs to be worked out by Apple, because it is back to WinAMP 3 for me until speed is improved. Even users with faster machines than mine won't be happy to burn up cpu cycles for nothing.