Pros
Good experience for junior lawyer or patent analyst starting out. Salary is above-market -- if you're not able to find a full time position at a firm. There are a few perks -- for example a gym membership, great coffee, food/snacks in the office. You can scrape by as long as you're not really horrible. Good on-the-job training. Office politics - great for developing those soft skills to get ahead.
Cons
Salary is below market compared to associate level compensation at a law firm. Year-end bonuses are highly discretionary and the determination process is far from transparent. Turnover is use to be high. Now, mediocre people can slip by without getting fired as long as they are savvy with office politics. Training isn't really there -- you are expected to learn from the job. Lots of people, even in the upper ranks either don't know what they're doing or are downright clueless. Office politics are less than ideal. People are very competitive (a good thing) but many don't understand teamwork. Some take the competitive thing a bit far and will do anything to get a leg up on a co-worker so watch your back!