It's a tough language to learn on your own, in part because the syntax is so flexible. You can essentially form a sentence with all the words in the wrong order and someone would still more or less understand what you're saying. Of course, formal Hindi does have "rules" but they aren't consistent across the materials I found.
Another issue is formal vs conversational Hindi. The materials all teach on formal Hindi, which is good, but on the other hand you'll sound awfully stuffy speaking formally to someone who's accustomed to, say, bastardized Mumbai Hindi (which itself is kind of an amalgamation of 3 or 4 languages).
The books don't teach you much that's very useful. I remember in one book I got, one of the first things it taught was how to ask someone how many siblings they had...
The NCSU materials were very "throw you in the water and try to swim."
Frankly I'd just go with Rosetta stone or find a tutor.