What is your opinion on the Unreal Engine btw?
Heavy (file size and performance cost), but exactly what a fully featured engine should be like. I actually think Epic are under-valuing it on their license agreements, but I'm not complaining if it means more people flock to it.
Is it something beginners should still be okay to use or should a different engine be chosen?
It's the training bra of engines. Use it for learning, hobbying or rapid experimentation/testing, but don't go any further than that if you want to get professional.
What makes it a bad engine exactly?
Why does everyone hate Unity anyways?
I'll give you a specific example from today. My boss committed a 120kb series of script changes, alongside a couple MBs of graphic files to our Git repo. I pulled the changes into my local copy and launched Unity, which then took exactly 2 hours, 43 minutes and 22 seconds to process the changes before the project actually opened, at which point it cited a number of broken meta file references, despite the fact I physically looked at the references and they aligned correctly.
Unity might claim they're "mobile friendly", but when you have to spend 3 hours waiting for the project to "convert" itself to a specific build mode, that's when you know it's been made by incompetent richardheads. Unreal doesn't have Modes for each platform, it's just unified up until you create the final build to try on a device/distribute.