Pros
Fun going out and talking to people. You will interact with people everyday. You control how much you get paid. Lots of flexibility in the time between accepting an order and traveling to the store and beginning to shop. It isn't pedal to the metal to get to the store like DoorDash is. You can also cancel batches after accepting as long as you keep your rate under 15%. This is different from DoorDash where your rankings will suffer if g.t. 2% cancellation rate.
Cons
There's a learning curve and it takes a while to learn each chain of stores' items. Once you become proficient at one store, the algorithm will lowball your offers relative to other less-experienced Instacart shoppers. Overall, Instacart shoppers likely get paid similar or less than the store's regular employees.