I had the demo, but it didn't enthuse me. you can check out the main beats http://ga.clubcubase.net/downloads.html#demo_songs and see if you like the sound of them but I found most of them weren't for me.
I think GA is very good, the presets (of which there are hundreds) and the kits (they go back to the 50's) are also good. The real power comes from hand editing the midi, you an record the midi into a channel and then play around with it. It's got wet/dry sounding, "humanise", you can tweak the volumes of each instrument. All good stuff.