Pros
Impeccable quality of translations. I worked with them for 15 years full-time as a freelance linguist at a regular pay of £28/$31 per hour - and often earned double the rate. I never had any problems with Lingo24 and miss them very much. There were always fast responses by friendly and helpful project managers, easy communication via PMs with the clients, great service to both customers and freelancers, well thought-through working processes, and efficient quality control. Now all gone.
Cons
Since the acquisition by Unbabel in 2022, sadly this excellent company has been gradually destroyed by the new owners who pay officially "up to $18 per hour" and effectively something like $6 (! horrific, isn't it), and they expect their editors to fix one page of bad machine translation in 2 (two!) minutes - while old Lingo24 paid us 20 (twenty) minutes for the same work and gave us plenty of extra time for research and double-checking.