Yes, Crossover is very good for stuff they've tweaked it for. Effectively it emulates all the calls and responses that the application needs, it's not a virtual machine in the same way the Parallels and VMWare are.
I used to use it to play Eve-Online with the Windows client because it worked better than the native OS X client but now the native client has improved somewhat, I don't use it any more.
In fact, if Crossover hadn't been available for me to play Eve, I'd probably not have gone Mac.