They've really gone downhill since the merger a couple of years ago. I had a great experience with Elance and then saw that Upwork was nothing but a garbage site with $5 jobs, so I didn't transfer my profile.
Then they add insult to injury by upping the fee to freelancers to 20%, on a sliding scale: the more money you make with a single client, the smaller the percentage they take but you have to hit something like $1000 before you get a break. Since most jobs are one-off and under $100, they are killing their freelancers profit margins. Greed like I've never seen.
They also are having problems with hackers. They get into the site easily posing as clients and employers. NO FILTER system to keep them out. UpWork relies on the freelancers to spot the scammers. Disgusting.
If it's any comfort, the site is in real, not imagined, decline, per Alexa's website ranking system. See their graph attached.