Pros
Most of the day to day work was interesting, challenging and generally well paced. The colleagues I worked with almost universally talented, committed and fun to work with. Neustar's financial position at the time was great and were able to engage in acts of largese at will such as an anual developers conference uniting developers from across the country at high profile national locations.
Cons
Strategically the company didn't seem to show any consistency and lacked the ability to see through plans. Financial planning was throughout my 3 years subject to wild swings. Ultimately what ended it for me was closing the San Diego office I worked in, as part of a grand plan to unite all the west coast offices into Mountain View. A month later they announced they were closing Mountain View and moving to San Frncisco. They have subsequent rented a large amount of office space in UTC, about 5 miles from where I previously worked. Looking back it wasn't much of a surprise. I witnessed Neustar gut the sales team, in a management initiative to cut costs (and experience) of the sales team that our business unit never really overcame. They also had a (consultant led) plan to streamline managent titles which ultimately pissed off a lot of people by taking away their titles but achieved nothing else. In my time I had 5 managers. I think the inability to hold onto middle mannagers was another major company failing My takeaway was a tone deaf senior management team that consistenyly wanted to interfere and never had the ability to make their choices work.