I'm currently doing the BGS material, with module 3 coming up soon. I'll have it all completed in 6 months, and that includes working full time, and having a month gap to renew an IR (that expired nearly 2 years ago).
I did have some background, holding a CASA (Australia) CPL, so it wasn't all new to me.
The fact that the material is so concise is what I love about it. When things drone on, that is when things start to blur. All the material that Bristol covers is relevant for the exams. Their revision week is good as well. They go through just about all the material quite quickly, while skipping the easier or less tested stuff.
So far, all passes, with no real difficulties.