Pros
The opportunity to skip banking and go right into PE at a well respected firm is huge. It's hard for people who have never experienced bulge bracket banking (which I'm assuming is many of those who left negative reviews) to understand how brutal those two years are. Audax works you hard but the work you are doing is value add and you are given an immense amount of responsibility. You work directly with the senior individuals at Audax and at your portfolio companies. Audax has a free matrix staffing model which means you end up working on a wide variety of teams your first couple years before you start to gravitate towards certain individuals. While this does mean that you have to adapt more at the beginning it is a positive opportunity to get exposure to different work styles, investment knowledge and leadership styles. Audax covers such a wide range of industry niches that you can seek out staffing on cases you really enjoy. Since you cover 4-5 companies you are bound to have one you don't like or is struggling, but that's a part of life and something you'll experience everywhere. It's one of the best places to get a serious breadth of industry knowledge. Deal reviews are open to everyone in the firm so good opportunity to soak up information. Also, they just closed on a ~$2.5b fund (only took three months so you can guess what prior returns have been) and are aggressively expanding so it's a great place to be.
Cons
Yes, the hours are tough but they aren't any worse than banking by any measure. If you are going to work all those hours wouldn't you rather be doing value added work than churning out pitch books? Also, if you learn how to utilize the infrastructure that Audax has put in place (in-house lawyers, marketing, capital markets, and tax people) you spend your time doing important stuff and don't waste hours on menial tasks.