I've heard more than one highly respected investor describe investing in US Treasuries today being all risk and no reward.
It is pretty hard to argue with that given the record lows Treasuries interest rates are at. Of course many people have been saying the same thing throughout a 30 year Treasury bull market.
For a completely different view, the video below has Robert Kessler making the bull case for owning US Treasuries. He has been happily long Treasuries for years, and is still long and strong.