I've used both the 5420 and 5430 for two and three years, respectively. My impressions are based on personal experience and are well-informed. The cases are identical, so it's not an issue of receiving a faulty unit. However, the paint is extremely prone to scratching. After just a few months in my backpack, both laptops showed noticeable marks from zippers and chargers—something I've never experienced with my ThinkPads or EliteBooks.
The plastic quality is subpar, and I constantly hear cracking noises. The keyboard is, at best, mediocre. As someone who types frequently, it quickly became clear that this device wasn't a good fit for me—but by then, it was already too late.
The touchpad is a disaster. In my 30+ years as an IT enthusiast, I can't recall encountering worse sensitivity. More often than not, I have to press firmly and repeat my actions multiple times for the device to register them.
Lastly, the battery life falls far short of the claimed performance, and the battery in both devices showed significant degradation after the first 50 charges.
If the times weren't so challenging, I would replace both of them immediately.