I've used Shiny Groove for hundreds of hours now and have not noticed a single flaw of its own - that is, not already present on Grooveshark on the browser, which I used to use heavily.
Furthermore, Shiny Groove's RAM usage stays the same, whereas in my experience that of Grooveshark on Safari grows steadily to the point that after sometimes less than an hour, Safari will inevitably stop responding and I had to restart it. So, if only for that, I couldn't be happier with Shiny Groove!
Oh, and it also works with the Back, Play/Pause & Next keys on your keyboard, which is so welcome!
So I do totally recommend it to any heavy user of Grooveshark familiar with my experience of it, or who just would rather enjoy Grooveshark separate from their browser's tabs, or who would pay for the ability to Play/Pause… Grooveshark from their keyboard or keyboard-controlling iOS app.
Of course, I'm not even remotely affiliated with whoever is responsible for SG! Just felt they deserve kudos for a practical, wholly functional piece of software that I'm so glad I found. Cheers!