I like how user friendly their platform is, It's extremely intuitive! We use them to build enterprise-level web services that handle multiple customers/projects at once; They have helped us get those projects done quickly with high quality results; The customer support has been stellar & very responsive when needed (even after hours!).
There was nothing in particular i disliked about using or working via jMix as far more than not having any dislikes whatsoever.. Honestly you should try it out because they were able to hit what we originally wanted right off the bat without much tweaking required afterwards unlike other options which had issues along the way such as taking longer then expected etc... The best thing about this is that it can be used in any type or size project, as its ability to scale easily with your requirement's without adding much overhead cost while managing cloud native data services like AWS Lambda etc., Also support most popular frameworks including Spring Boot 1-8 & 8+, Angular 2+ (Angular 5) Node JS ExpressJS ReactJs Vuejs Webpack Typescript Asp Net Core.