As a dev or more on the ops side? How long are the contracts? When you get a client, do they place you in a team with internals, or is there another setup? I guess toptal is like an intermediary, global scale, and they screen/test their freelancers.
It has varied from me being the only person working on it to full time work.
It's been easy enough that I've always taken 2, 20 hour/week jobs so that I don't lose all my employment at once when one ends. It's never been a problem picking up the next contract.
I've never worked with anyone else from Toptal, though I have been the replacement.
I haven't been using them for a while, but it's been non-stop inquiries from them, even though I've set my availability to 0hr/wk.
When I started the process years ago, I only saw bad things about Toptal. Went through anyways and have only good things to say. The most vocal are always the negative, and a lot of them were people who never got through the selection process. YMMV, but my experience is positive.
Yes, the interview process is a bit long, but opportunities have been non-stop for several years in a row now.
Never an issue with pay, although it can border on 6 weeks in arrears due to billing cycles with the client and bi-weekly deposits from Toptal.