I have Kettlebell Express and Kettlebell Express Ultra, and I have done two other programs by Geoff Neupert (Kettlebell Burn 2.0 and Kettlebell Strong).

I highly recommend Geoff's work in general. He's a great teacher, and I think he's great at intelligent program design in terms of progression, fatigue management, etc.. One thing I would say about Kettlebell Express is that you should take very seriously what he writes in the opening pages of the PDF about the difference between programs and workouts. You are not going to be successful if you bounce from one program to another because they all do different things. So if you're a person who gets bored easily, this will probably not be right for you because most of the programs in this collection are fairly monotonous in terms of the movements themselves, though, obviously, they get progressively more challenging.

One thing I do take issue with Geoff on is his insistence that you not do any other kind of training while doing his programs, most of which are only 3 days a week for 20 or 30 minutes. He recommends this because he thinks people have a tendency to overtrain when they first start a new program, thinking the more work they do, the faster they'll see results, which ultimately leads to burnout. But as a very petite woman, losing half a pound a week takes every ounce of effort I can summon, and if I only worked out a grand total of an hour per week, my diet would basically have no room for error, and it would take me a year to lose my last 13 lbs.

Overall, if you have the discipline to stick to his programs and get your caloric deficit solely from your diet, then I think you will see slow but steady progress. You will definitely get stronger and better at kettlebell training.