I think I could give a bit of insight since I actually use Roger.
As of now, I definitely think WTB should be used supplementary at this stage of Roger's new software. I originally got my Roger package in 2013, so it came with the Wiley books as well. I'm studying for REG now, and bought the new 2014 edition of the textbook, which doesn't come with Wiley. However, I've been still using the Wiley textbook that I got with my original package, because Roger's software doesn't seem to be at 100% yet.
The interface to choose questions is a bit awkward, but that's no big deal. Also, the format of answering the questions seems pretty good, with the timer and answer explanations being good touches. I think the problem lies with the organization and the amount of questions. For example, the Wiley textbook had 200+ for individual taxation, while Roger's software had just a bit over 100. There are also some sub-sections that come up with zero questions, while some sections have a ton and seem to lump other sections within it (ie: itemized deduction questions being in the gross income section). There's also times where some of the questions will repeat, even within a single sub-section.
So overall, it's a good start for Roger, but there's definitely a ton of tweaks that need to be tended to. If I were you, I would definitely download the WTB, and if you could get your hands on any Wiley textbooks as well, those are great for doing tons of MCQ's.
BEC: 88 (8/27/13)
FAR: 93 (12/3/13)
REG: 92 (2/27/14)
AUD: 95 (4/22/14)
Roger CPA, Wiley Test Banks, NINJA Notes & Audio