That's a pretty good beginner bike. I wouldn't buy a bike with an engine much bigger than that for starters, but you'll be fine with it.
As for the price, that is a little high for that bike. The blue book on it is $4200, so I imagine you should be able to get him down at least that low - it depends on a lot of things: has he added any extras to the bike that would increase its value? Is he desperate to sell it (the more desperate he is, the lower he is likely to go on price), has the bike ever fallen down or been damaged? Knowing things like this and using them to leverage the price down will help you. Detach yourself from emotion (I know it's your first bike and you're totally excited, but emotion will cost you in real dollars) - make the sale with a cool head about you so you can notice things you need to be able to notice to make a good decision about whether the bike is worth buying.
Good luck, and congrats on whatever bike you choose!
