A general rule of thumb I like to follow is wait a few years. The latest and "greatest" aint always so great. UEFI (Unified Extensible Firmware Interface, new to Win 8) which replaces BIOS seems like more trouble than it's worth, due in part because of its reliance on certificate authorities (It also breaks dual boots, unless you have a workaround). Apparently MS hasn't learned that CA's are not all that secure. Also, UEFI is bloated as fuck as it offers a shit ton of functionality, which could just lead to even more vulnerabilities. It just seems like another way to get the world singing MS's song. You can disable it, but still..
Other than that, I don't really have an opinion. Some friends say performance differences can't really be felt but it does appear to handle memory more efficiently
But I say if it aint broke, don't fix it. You can always upgrade later on. And chances are, time will allow some of the glaring bugs to be ironed out, fixes to surface, etc.