Pros
Pay is good, and even at times when you aren't as competent as some of your peers are, if you keep founders and seniors ego flattered you should be getting more respect and money.
Cons
1. You wouldn't know anything as compared to peers in your industry, so if you are stuck here for a long time you are a slave to the company. Getting a job outside with pay comparable to similar experienced people would be become harder and harder with time due to lack of knowledge.
2. You lose your thinking ability and dont even question why the thing you do there works, brain gets slower here with time.
3. If you don't play the game well enough even if you try things they'll never get noticed. You need to put intensive effort into making it look like you are doing work even if you are not doing work.
Advice to people who wanna continue long: Don't try anything new at all even if you want to, just do the work assigned to you without any mistake, and try to massage egos of founders (and specially seniors). Not screwing-up is very important here, if there's a screw-up make sure you aren't the scapegoat.