Any views on life on the inside? Culture? Career prospects compared to say big-4?

Its a partnership venture between Microsoft and Accenture ! I know people that have enjoyed it but you will be resourced mostly on ACN projects doing .Net

That depends on your skillset. If you're a .net developer, the above is true. But it also has ACN and direct client business in Microsoft infrastructure, ERP and CRM consulting. The latter two are particular growth areas, I believe.

Does anyone have details as to number of employees, project size, payscales. And also whether they are still hiring in this economic climate?How similar is their work culture to Accenture? I Do they only hire people with MS certifications?

They do not only hire people with MS certifications. But they do require you to get certified within a certain time period (they'll pay for the exams).Culture is generally more relaxed than ACN. Not so much of a presenteeism culture. You get to go home on time more often.