There are some freebie videos on Audiosnap on my youtube page and it's covered in depth in my SWA X2 Complete video (links for both in my sig).
Audiosnap isn't the most intuitive part of the program but I've found that a few basic housekeeping tasks before use make a huge difference to how successful you'll find it.
One of the most important is to trim and bounce clips before even opening audiosnap, stray noises such as studio chit chat at the start of clips will create havoc.
Make sure the project tempo is roughly correct before starting which will save a heap of time adjusting the tempo map. Drag clips and line up the first down beat with a measure line also helps.
An accurate tempo map is also important.
After I spent an awful long time using a "suck it and see" approach and finding out about some of those tips the success I had with audiosnap went up tenfold. The biggest problem I used to have was the dreaded "tempo out of range" - bouncing the clip will stop most of that. It's caused by errant transient detection and Sonar thinks it has to generate a tempo greater than 1000 bpm to compensate, hence the message.
To summarize I find it works pretty well (I'd even argue very well) but it does take some learning and could certainly be more intuitive.