Not every GUI experience can be as smooth as Apple's iPhone (and it still has more than a few annoyances). From WinMo 6 to DirectTV's HD DVR to Windows 2.0, oobject's collection could bring back some bad memories. [oobject]
I never tried the DirectTV HD DVR, but my experience with a Dish Networks DVR back in 2008 wasn't anything to write home about, either. What's the most over-the-top, least intuitive interface you've ever had the misfortune to use?