seamale--basically, you get a dedicated relationship manager, access to HSBC's global network (whatever that means), a consolidated statement, some better rates (though still lower than rates offered by other banks), some fee waivers and other features that you can check on the HSBC website.
If there are other significant benefits, please let me know before I close my account!
I only upgraded to Premier because they were offering a free ticket to Bangkok for doing so. The dedicated relationship manager isn't really a benefit to me, as now I have to deal with unwanted calls from this person. The recommendation I got from my manager was basically to buy unit trusts loaded with high fees. I'm pretty sure you can get this type of financial advice without having a Premier account.