Pros
There are not a lot of benefits. However, you can learn to communicate and make relations. You will earn customer skills and how to be patient. You can easily get to touch with direct airline's employee. If lucky then you can get a chance to work directly for the airlines in future.
Cons
I recently worked for them as a PSA and trust me the experience was exhausting. They always want you to work but don't want to pay. The payroll is always messed up so you have to check your punch in and punch out times every day to make sure you are getting the right pay. Sometimes they want you to work overtime but this company don't pay the overtime since it is against their company policy. The management sucks a big time. Supervisors don't know how to manage their team. For full-time, they don't even 30 mins break which is required by law for full-time employees. Always beware that they can put you in any position so it is not limited to check in passenger and you can't oppose. The life sucks as PSA so I suggest don't apply and find a much better job or apply direct from airlines.