Avantages
I worked as a contractor for National Technology Rentals/Avelco/National Technology Leasing for 3 years. The company name changed more times than I can remember.
You get responsibility you probably aren't qualified for. So if you're a competent person you can learn and get put in situations you can grow from.
Inconvénients
The owner does not pay on time, if at all. Checks bounce for full time employees who have been there 10 years (why they stay I'll never know) so if you're new or a contractor, expect getting paid to be its own part time job.
The equipment is laughably old and bad.
You are sent into jobs completely blind and without the proper gear OR working gear.
The owner has a mob boss mentality who expects the world from you, but don't take anything he says at his word cause he will gaslight you and make you feel like you're taking crazy pills. You're not.
The company has HR (apparently) and accounting dept (apparently) but it's really just the owner doing everything. No one else has the ability to sign off on even buying pencils.