Pros
1. HR is very nice and friendly. 2. Their immigration process is very good. I had my H1B approved thrice and also my green card was filed by them. I never had any issues. What I liked most is that HR really understands the pain that immigrants goes through and try to help you with the best lawyers possible, keeping communication very much open with all parties involved which helps in creating very good paper work. I worked there for 5 years and never had any kind of problem. 3. Nice 401 k. I think for your 5% saving company matches 4%. 4. I used to get around 18 PTOs which I felt was nice as I was working as a contractor. 5. They do one Christmas party every year where every one meets. I haven't seen this kind of culture in other consultings much. 6. I asked that I want to change client because I was looking for something else and within 6 month's they gave me opportunity to work with other client. I think Sigma listens to their employees concerns (especially if you have worked for them for long(3+ years)) and try their best to handle it.
Cons
1. Medical Insurance used to be much better earlier. 2. Yearly salary hikes could be better.