Upwork is very user-friendly and intuitive. It is a great platform if you are new to freelancing and looking to build your client base. As you grow, my suggestion would be to wean yourself away from Upwork's services, mainly because of the fees. If you are ever going to go full-time freelance for a living, you will need to be free from Upwork's exorbitant fees.
Takeaway: Great for beginner freelancers. Not good for long-term, full-time freelancers looking to make a living from their work.