I spent about 6 months trying different CAM software before investing in SprutCam. I finally picked SC because I could find nothing else in the market place that has the price / performance ratio anywhere close. Your ratio may be different than mine as much of it depends on what you want to create ,what your background is in figuring such things out with limited documentation, and if it's for a hobby or a business venture.
As for reference material Dave from the UK site has some training materials for a very reasonable price. I know of no available book or training other than the material Dave offers. FWIW, There are a few members here that have been very helpful in helping the new guy get up to speed.
I think all of us that have used the program will pretty much agree the initial learning curve is a bit steep. However, the developers and users are very supportive in helping each other through the rough spots. The program is very powerful and SC does provide updates and new features every month or so.
I am not associated with SC, just a user that is satisfied with the purchase.