I use Grooveshark daily. Aside from the excellent UI and service (couldn't tell you the last time it was down), the catalog is incredible.
One thing to note, though, is that they do pretty well with takedowns. For example, I attempted to upload a copyrighted song years ago and uploads were disabled on my account. They also work with publishers and artists to ensure fair compensation is made.
I've paid for the Pro account for a few years now and strongly believe they could do better than their competition if they made the service paid-only.
This must be a very recent development then - there have been countless stories of rather obscure and niche artists that found it impossible to have their work taken down by Grooveshark. Instead these reports often suggested that those (re-)uploads of unlicensed material seemed to happen automated.
One thing to note, though, is that they do pretty well with takedowns. For example, I attempted to upload a copyrighted song years ago and uploads were disabled on my account. They also work with publishers and artists to ensure fair compensation is made.
I've paid for the Pro account for a few years now and strongly believe they could do better than their competition if they made the service paid-only.