What do you like best?
After working with various off-shore vendors, Birlasoft has risen to the top. They consistently provide capable technical resources, are willing to go above and beyond, and continue to impress me with their turn-around-time (time from request to working prototype).
What do you dislike?
While Birlasoft resources are some of the best Salesforce developers I have ever worked with, they struggle at times with myopic thinking - and need a bit of strategic direction. Of course, none of that has hindered their ability to deliver what was asked of them.
Recommendations to others considering the product
The key to success is a strong on-shore resource that you can make a partner on your team. Utilize this person as your development lead and treat them as part of your team.