There are cheaper CRM solutions, but evaluate what your needs will be... if you are operating at a large scale, you'll need one of the large players like Oracle RightNow. And it is robust and effective and good for large-scale use. I really, really love using this system!
Other tips: definitely have someone be in charge of analytics, and then send them to the Analytics training course. Expect extra time (and cost) for integration or implementation, because things are always complicated at this scale. And when designing layouts and workspaces, consider foremost the agent experience. Ask the agents what they need and use, and work from there... rather than deciding what they need and then forcing it upon them. Find this out, address it, and then constantly re-evaluate against it.
As I've mentioned elsewhere, a big weakness is that it does not have an API to integrate with common WFM (workforce management) applications. If you're going to need this, this could be an issue. I've dinged it points for this.