I recently received an offer from Bain after almost 5 months of preparation. PrepLounge was incredibly helpful.
1) Live practice: I met several extremely motivated, hardworking and intelligent people throughout the process. Live practice cases simulated the stress of an actual case (invaluable). Being able to consistently schedule challenging practice cases online was simply a gamechanger.
2) Math: The online math tool, from easy to hard difficulty levels, allows you to gradually become proficient in "on-the-spot tough calculations". The rankings also provided a nice competitive aspect, pushing me further.
3) Practice cases and brain teasers: Apart from live cases, re-reading practice cases and solving brain teasers not only expanded my knowledge of scenarios but also became a daily mental workout. All in all, thank you PrepLounge.