Yes, its very necessary to check the history of previous projects if any of the builder. I have posted a review on one of the builder please read for more info (http://www.commonfloor.com/forum/50717383611a7-review-on-s-v-sowmya-developers)
But many builders show the last 5 years picture only.. like how many projects they ve done recently.. but this builder gives a warranty.. like if anything goes wrong to the building in the next 5 yrs he will repair it free of cost..