It is good to have all the necessities of a household at one place. This is what forces you to visit these bug stores. But major challenge I see there are as follows :
They design the packages with two or three important products and attach two or three products which may not be that useful to you, thus forcingto buy unnecessary items. These item are usually their own brands.
They have almost every product of their own inbuilt brand, and price them too high and then offer huge discount thus showing big offers on the cart.
Usually they sell big packings. Like in. Pulses you are least likely to get half kg packs and at times even one kg packs, thus useless for small families. Either they buy extra and let it become outdated for lesser use in their home or look for traditional market.
You are least likely to get all your needs in one go. I never got everything in the pack I require in last eight years I am visiting Big Bazaar. So what is the use of such a big store.
Quality of their own brands is so poor that you cannot compare it with good brands.
Offers are limited on reputed brands but during their bug sake days you are likely to get them is the only positive.
Staff is usually cooperative and good.
Their card scheme is blunder at hardly 3-4% gain. Although they misguide their customers with 20% extra. Just calculate on excel what you pay and what to you get, it is not above 4%