I recently got a Zeewei DSO3D12 to replace a DSO154 - main reason for replacing the latter was that I accidentally cracked its screen.
If you are familiar with the DSO154, the DSO3D12 will feel very similar in terms of UI - even though it has quite a few more buttons to control its operation. The latter is a good thing, I'd say, increasing the convenience of changing time base or vertical scale in particular. The one thing that was mildly annoying in the UI is how to move up and down in the menu - annoying only because I could find absolutely nothing in the manual to tell how to do it. I had to try various buttons until I finally realized that it treats the column of buttons next to the display as "soft buttons" to select each menu section. Within the menu section, the arrow buttons and OK button work as expected / much like the DSO154.
Is it worth the extra $50? Well ... jury is still out on that. I mostly just wanted something portable and battery powered for times when those attributes are needed. Dual channels is definitely a plus for the uses I have in mind for it. An actual case feels like it might be less likely to succumb to damage than the DSO154 proved to be. All in all, I have no buyer's remorse; it's just hard to get as excited about this for $80 when I had something that felt and looked very similar for $30 - albeit only 1 channel, smaller screen, and lower specs.