I went through NACA. Great program with great benefits. Depending on your situation, it can be really easy or really hard. If your finances are straight and your credit report is clean, you'll breeze through. If not, you'll spend a lot of time cleaning that stuff up.
The main barrier people have is the time to close and the overall duration of the process. If you're house hunting and trying to buy within a month, do not do this program. Some sellers aren't willing to wait weeks to complete back-and-forth paperwork and some buyers don't have the patience to deal with the requirements, especially if its in a hot market.
I purchased a new construction home so I wasn't in a rush to move in. My counselor was great and quick to respond to calls and email. I can't say too many programs beat their closing benefits and interest rates. I made too much to benefit from other housing programs in my area.