ManyCam

Pros: There is nothing good about this software. It is not user-friendly, has terrible connectivity, there were always issues with sound every time I used it, and their customer service is completely unhelpful.

Cons: Difficult user interface, connectivity issues, problems with sound echoing or no sound.

Terrible customer service. Exchanged multiple emails with them and they were unhelpful. I tried calling the corporate number and left many messages and no one ever responded.‘s

It seems like they don’t care about keeping their customers happy.

Overall: Terrible experience with many problems and poor customer service that was unhelpful. I lost business because I used this terrible software. Don’t bother wasting your time or money.

Pros: Once you get used to some basic concepts, it's very easy to set up multiple "camera angles" and channels of video content, including Picture in Picture, and perhaps most usefully, overlaying two video streams with the front one with a transparent background. For example, to put you the presenter in front of your powerpoint slides so you can point at things, and still advance the slides.
Switching between channels is straightforward, either a fade or a cut, and you can edit a channel whilst broadcasting on another, which is great for adjusting the green screen when the light has changed, and to place your three PIP participants for the next round of an awards ceremony.
The resultant broadcast can go anywhere you want it to - I've used it with Zoom, GoToWebinar, Teams, and Hopin
Has useful features like bottom third (your name and title) and clocks.

Cons: Since it's on your computer, all the streams have to come to your computer before they can be combined and broadcast out, which could create problems with bandwidth if you have a lot of external feeds.
It took me a while to get used to setting up multi-layer (Picture in Picture) channels, and I only found out you could edit one channel whilst broadcasting another in the last couple of weeks.

Overall: Makes presentations, speaking, and even being a participant a much more sophisticated and professional experience. People might not know what you are doing, but they will know subconsciously that you are doing it well.