When Spotify first came out, I wanted an account BAD. It was one of the first sites of its kind that didn't allow you instant access (or that I didn't personally get an invite to or a beta invite right away.) I admit, this may have made me want "in" a little bit more, but from what I had heard about the site, it had enough to get me interested and I requested an invite.
It took about a week or two and when I got my invite, I hurriedly signed up and downloaded the application to my computer. I immediately synced it with my iTunes library and even connected it to my Facebook. (Note: This was BEFORE Facebook had added the Music sharing option, wherein they have all of your plays show up on your page/newsfeed. I loved this feature because it showed me who of my Facebook friends was already on the website and allowed me to access their profiles and their playlists. It also showed me which of my music-hungry friends were not on this site yet, and after another couple of weeks gave me the ability to invite friends via email, and then Facebook.
Now, about the actual application: it rocks. There are SO many songs, so many version of songs, the playlists and layout are so simple and easy to change, delete, add, and move around. I've never found a free music website/application that was so simple to use and had so much variety. It also suggests different music to you, allows you to see what's popular, and gives you insight into "new" tunes so that you can expand your musical palette. It's also fantastic because if you download the application to another computer, the specific tunes you have imported from iTunes are still available to you through the Spotify app.
I continued to enjoy the site, but wished that there was a way to access the database through streaming, like Grooveshark or Pandora, because sometimes I'm using a public computer, or I'm at work, where you need an administrator log-in to download any time of application.
Take a short break and "SUDDENLY" Facebook has full access to Spotify and vice versa. Everyone and their mother can sign up on Spotify and link up to Facebook. Now, when you play things on Spotify - everything links to Facebook and your friends can view it on your profile, in the music section, and in the newsfeed. Spotify did add what they call "Private Session" where you can be logged in/synced to Facebook, but not post your songs as you listen to them publicly.
At this point, I chose to stay on Spotify and not sync to my Facebook account. I will miss being able to see my friends' Spotify accounts and playlists, but it's a price to pay for privacy.
On a bright note, a big point-winner for Spotify, they somehow made the application downloadable without Administrator Rights. I can't give it complete access, but I was able to download it to my work computer without needing to fully install it, and this makes me incredibly happy.
So, overall, I give it a 9/10 as a free music application.
