Pros
Advent operates in a narrow, deep, requirements-intensive technology and industry niche, which influences much about how the company is managed and how it can grow. Given these attributes of the business Advent happens to be in, it is an exceptionally well-managed company and a great place to work and to develop deep competence. Two critical things Advent must constantly strive for: 1) it must be a reliable vendor for its customers. Among other things, this means Advent must take longer to release technology, because the design and testing phases are so extended; and it means Advent actually cannot take many risks, because it will disrupt customers if something doesn't work. Unlike many companies in the San Francisco area, Advent cannot easily "try" things to see what might work; everything has to work as soon as it's announced to customers. 2) it must be staffed with people who combine functional competence (ie, ability to write software, ability to sell, ability to market) with extremely deep, focused domain knowledge about investment management systems (ie, the difference between hedge fund traders and institutional traders, the difference between the transaction records of various fixed income securities, etc). The depth of this domain, and the kind of people attracted to it, can be almost crazy at times, but successful people at Advent and in this line of work must care about the details of the domain. On balance, Advent meets these objectives. In my experience, senior management cares deeply about whether the technology works for customers, and spends surprisingly significant amount of time thinking about employees and their well-being. They don't always get it perfect, but the effort, intent, and overall track record is very positive. My view is that employees (and customers, for that matter) who get frustrated with Advent are not aware of or are not assigning value to the constraints that Advent must live with. The people who fail or get frustrated are generally the ones who don't understand the constraints, take shortcuts, or try to glide above the details. Contrary to some of the unfavorable comments here, in my experience senior management cared very deeply about the input and well-being of employees who know what they are doing, and talented people had plenty of opportunity to grow within Advent. Another correction to some of the comments here: there are senior people, at the very top ranks and throughout the middle management, who have deep experience elsewhere. Yes, there are many Advent lifers throughout all levels of the company, but it's not exclusive that way, and the lifers who have risen have all contributed significantly and earned their promotions. Also, I'd reiterate what many others mentioned on the good benefits and general work environment. Many commented on things like the dog policy. I'd also point out Advent's substantial focus on community service; for example, the company basically shuts down for a day every year so everyone can go out and do public service (this is in addition to many smaller service opportunities throughout the year) . . . Advent is not a very big company but has a broad and deep service attitude that is bigger than the size of the company would justify.
Cons
Given the constraints above, Advent's business changes and grows only incrementally, and every new step and commitment must be undertaken with a lot of care and planning. Therefore, Advent is not a "let's draw it up on the whiteboard and go for it" kind of company. If you are looking for a change-by-the-day Silicon Valley experience, you might be disappointed.