Pros
Pay is better than Big 4, in line with other boutiques. The firm has unique expertise in the Telco space, so you may get a chance to work on some major buyout deals in that space. Some interesting perks, including the ability to work out of any of the global offices after the first year, though they need to like you before you can enjoy such benefits. Junior staff are very talented and a pleasure to work with. Some of the partners are great (though most of the good ones have left). Again due to their telco expertise, you might have a chance to work on some international projects, though it's not common. There is opportunity to learn a lot of soft skills (especially from a handful of good partners) and be exposed to a lot of high-profile investors.
Cons
A handful of partners (esp. those who joined early) have outsized influence on everything, so if you are not on good terms with those few people, you will be pushed out. If they like you, you will grow in the ranks. Performance is secondary. One of those partners is especially vindictive and insecure, and if he doesn't like you, you can be out within months. The managing partner is not an honest, effective leader. This is not a real TMT shop. It's 80% telco work, and most of the work is CDD. So you end up working long hours on short deadlines with limited learning. Non-Telco work is low-quality and low-impact, even if you're lucky to get some. The brand is unknown outside some telco and infra investor circles, which limits your exits, though still better than Big 4. The culture is stuck in an 80s/90s grind mindset. They really don't care much about the employees, and the most telling evidence is the state of their offices. Most of their offices, including the Boston HQ, are outdated and cheaply furnished and designed, decades behind their competitors. Really depressive places that are procured with cost-saving in mind only. Middle managers lack EQ and any kind of desire to help ICs and juniors to grow. Very self-centered, and the firm promotes such behavior as well.