Pros
I worked at Kelvin for over 3 years and experienced the growing pain of a company finding it's niche. There was some turn over and product guidance problems early on, but the company has really found it's stride. The new product and engineering teams are able to define the product requirements and work together to develop the deliverables. Within a couple of sprints, the new Chief Product Officer was able to bring focus and direction to the product lines and a unified message on what was being built and for whom. I worked on the engineering side and it is a great group of developers. It's a multidisciplinary team with folks from around the world. Most everyone is nice and will to help out with problems you run into. (You'll also learn some Portuguese along the way!) Coming up to speed can be a bit of a learning curve, but there is always someone there on Slack to help you out. Kelvin was good about wanting to make sure you were working on projects that kept you engaged. There are always project you might not be too keen on, but the managers at Kelvin really wanted to keep you engaged and working on the things that can motivate you. There were many instances where folks would feel drawn to a different role and the managers were receptive and willing. Folks from engineering going to product, changing from backend development to application development, etc. Having the space to explore what you enjoy working on was refreshing in a company. Overall, I had a very good experience working at Kelvin and would recommend it to anyone looking for a fast paced, exciting career.
Cons
There can be odd hours and Slack messages at all times of the day. It's a smaller company with offices around the world, so somewhere, there are co-workers working that will likely have questions or a problem. When you are leading engineering teams, you need to willing to hop onto calls at all times.