Pros
This is a small(er) international firm filled with intelligent and highly motivated professionals. The firm grew rapidly which provided opportunity to advance relatively quickly in both title and in salary. The client base is complex and you don't get "siloed" into performing a single function, so the work is always interesting if you enjoy dealing with tax issues. Despite the increasing size, leadership has so far managed to keep the bureaucracy to a minimum and the engagement process pretty well streamlined. Unlike other big firms, there are very few extraneous documentation requirements, so it was relatively easy to focus on the actual tax work instead of wasting half of every day on administrative tasks. And because there's no audit group, all of the Independence paperwork is non-existent here, and you don't have to go through 5 separate departments to get a client onboarded. Also, while this is a CPA firm and you're always going to have long hours in this business, the hours are actually better here than at other comparatively sized firms. You'll have a lot of 10pm - 12am nights during busy seasons, but the 2am or longer nights are rare here (unlike big 4 types). Overall, this was a great place to learn the business of tax.
Cons
The cons here are mostly typical of any public accounting firm. Busy seasons are of course awful, lot of pressure to meet unrealistic budgets, and doing good work begets more work for little/no additional reward at the employee-level. While the pay here is competitive, there is very little monetary reward differential for the high-performers vs. middle of the pack, so the incentive to "exceed expectations" (i.e. work more) is not apparent. And of course there are also the few partners here who lack the ability to hold any concern whatsoever for the life-satisfaction of their subordinates. Unless you enjoy constant insult whilst working 100 hour weeks, the solution is simply to avoid working on these partners' clients and instead fill your schedule with clients of partners who actually do care (of which there are plenty).