Hyoho Niten Ichi Ryu is a very simple, somewhat ruthless form--it focuses entirely on effectiveness, and nothing else. As a result, some of the style's methods and tactics--such as striking at the hands--are considered "cheap" or "dirty" by other swordsmen...
...I've noticed that most of this criticism comes after they have been beaten by it.
There are really very few "techniques" involved--it is essentialy the basics of kenjutsu refined to the point where little else is needed.
It's only real weakness is that it is not good against certain styles from China and other counties--most notably the "Drunken Sword". Because of the similar foundations of traditional Japanese kenjutsu styles, there are some things the creators of those styles never thought to make a defense against.
To compensate for this, I have applied my theories of free frormed, unpredictable movement to Hyoho Niten Ichi Ryu to essentially "fill in the holes".
What results is essentially a calm, very focused style that can instantly become completely fluid and unpredictable--and then change right back, keeping the opponent off-balance.
If you want more information on the origional Hyoho Niten Ichi Ryu, I suggest reading "Go Rin No Sho" a book translated from scrolls that Musashi wrote at the end of his life. It outlines the basic form and principles of the style, as well as providing extensive information on tactics and strategy, and the ways to apply this knowlege to every part of your life--I hear the book is popular with american buisnessman for this reason.