After many through holes in wood, 1.5mm box sections, 2mm angle irons, and a few in 5mm sheet metal, I have to say it didn't struggle or overheat at all with the 4Ah batteries, which lost one out of three full charge lights after 3-4 hours of work.
Also, as a hammer drill with a 10mm bit, it drilled into concrete with impressive ease.
The only drawback I found is that the chuck is not as strong as the very high torque of the drill, and sometimes at the end of drilling, the small bits spin inside the chuck... something that can be fixed somewhat if you ease the pressure a bit at the end.
Nothing dramatic, and I give it 5* because in all other aspects it is excellent at an amazing price for what it offers.