Pros
Avaya has a very competitive compensation plan. They do not want brain drain to their competition. Avaya has a portfolio of well-known products that sit squarely upon the AT&T legacy. Avaya has the culture of a telecom company but the business model of an enterprise software company. Avaya has a new management team that is taking the challenges of building a new product portfolio very seriously.
Cons
After much transformation, Avaya is STILL held back by its own history. Fear is still the dominant reason why products do not evolve. Product managers seem to be risk-averse (nobody ever got fired for...). Innovation is seen as something that Apple, Google, and Facebook do... So execs often refer to these companies as fine examples. But Avaya itself is terrified of actually putting its own name on something new. I suspect that when Avaya management wants to create something new they probably hire a 26 year-old MBA who does a Powerpoint using Forrester and Gartner quotations and stick men. At the right moment, the youngster alludes to "social networking" and "open source", and the Avaya guys get all sentimental. If none of this bothers you, you should be fine.