My experience with the Premier can be summed up like this "A TiVo that only a fanboy could love."
With the HD UI, it might just be the slowest DVR I've ever used (if you know of a slower one, please share). Add in the fact that not all the "high traffic" areas have been updated and switching between UIs is a little jolting, and you have yourselves an abomination.
It's sad to say, but TiVo would've been better off only updating the hardware and leaving this software in the oven longer to cook.
Bottom line is TiVo is charging the same price as they were for the TiVo HD and all they added in the last 4 years, basically, was an HD UI that many will decide to turn off.
How good could it be if it isn't HD?