It definitely looks like a nice machine and probably the best competitor to the 15" rMBP right now (alongside it's twin the XPS 9570) but do a search for all of the QC issues on the Precision 5510/5520/5530 and XPS 9550/9560/9570 and you will quickly see that there are a huge number of problems with this computer. That said, you can configure it with Dell's "Next Business Day" international onsite service (which is more like service in 2-3 days, at least based on my anecdotal experience) which is a nice touch.

I've spent a very long time researching 15" mobile workstations for the last year or two since I will eventually need a replacement to my 2015 15" rMBP and I have come to the conclusion that pretty much every one of them has some sort of huge deal breaker for me. At this point I'm just hoping that my 2015 15" rMBP can last for another couple of years while we await some design refreshes from Lenovo, Dell, and Apple.