I think you all really need to try out the laptop before making a judgement.
I have the Precision 5510 (The professional line of the XPS 15 9550) for almost a year now and I noticed a HUGE improvement over the MacBook Pros in all areas from my experience.
1) Battery Life - On average I get about 5-6 hours of battery on the 15" MBP. Compared to the Dell Precision 5510, I average approx. 6-7 hours for the same usage. It's not a huge improvement but its slightly better on a day to day thing. If I feel I cannot survive with 1 charge on the MBP, it'll be the same for the Dell and vice versa. However, if you compared to paper; the Dell has vastly better battery performance. The larger 6-Cell battery on the Dell is rated at 81 Wh. The MBP comes with 95 Wh. For something that's quite bigger but getting same or almost the same real world performance? Yeah. the Dell really beat the MBP on this one.
2) Performance - Raw CPU performance is the same. I have the Xeon E3-1505M processor on the Dell and on paper it is slower than the 2013 MBP with the 4960HQ. However, during everyday usage including handbrake conversions, the performance is about the same with the Dell beating the MBP on some areas. Remember, because of the laptop form, thermals plays into a huge part in performance and the Dell just has better thermal performance for me. It ranges typically around 35-75 deg C at any given time since I've owned the system. The MBP usually ramps up to upper 90s but shy from 100. During the last Handbrake conversion, the MBP hit its thermal ceiling and needed to throttle back away from its max rated turbo speed. The dell chucked away at its maxed rated turbo speed the entire time with no throttles at all.
3) Memory - 32GB vs 16GB. Can't beat it. Just face it. Don't try to fight me on this because its not about who's right; its just simple common sense. The other day, I was playing Civ 6 running at High + native 1920x1080, running macOS 10.12.2 in a virtual machine with 2 vCPU and 16GB Ram AND running ubuntu linux in a VM with 1 vCPU and 8GB shared to the VM along with Chrome opened with approx 15-20 tabs, outlook, messenger, a number of background apps and streaming airplay onto the TV and I was able to switch back and forth between ALL apps with no lag whatsoever. Did not even have any slowdown or wait for the game to reload all the graphics at all. It just ran and ran wonderfully. My total RAM usage was approx 27-28GB total. No matter how optimized macOS is or the MBP, its still limited by the available ram.
4) Graphics - I have the nVidia Quadro M1000M with 2GB ram on the Dell. It blows the nVidia GeForce 750M 2GB found in the MBP out of the water. Just take the Civ 6 game for example. On its built-in benchmark, I get 15-20fps with 1920x1200 @ Medium settings. On the Dell's Quadro card, I get 40-50fps @ 1920x1080 with HIGH settings. That's on a workstation, professional card. Imagine if it was its counterpart (960M) it would be even slightly faster.
5) SSD Performance - This is probably the only area that the MBP really beats the Dell. Compared to the 2013 MBP, I only get 700-900MB performance. On the Dell, I'm getting about 600-900MB performance. Not the best but pretty similar and overall, I think the MBP is a bit faster.
6) Form - The webcam position sucks on the Dell. Enough said. Overall, the Dell is smaller, sleeker, looks better, possibly lighter but I can't really tell between the two. The small bezel on the Dell just beats the MBP hands down. The touchpad works just as well; much better then any other PC's I've used. I can easily say the Dell's touchpad is equal or just 95% equal to the MBP's touch pads.
Full specs of the Dell:
2.8GHz Intel Xeon E3-1505M (3.8GHz Turbo, 4 Core, 8 Threads)
32GB DDR4 2133MHz Non-ECC Ram (2x16GB)
512GB Samsung nVMe SSD Integrated w/ Encryption
2GB nVidia Quadro M1000M Graphics Card
15.6" LED Backlit 1920x1080 FHD Non-Touch Matte Screen
81 Wh 6-Cell Integrated Battery
Full specs of the MBP:
Late 2013, 15" Model
2.6GHz Intel Core i7 4960HQ
16GB DDR3 1600MHz Ram
1TB Samsung SSD, Apple Branded
2GB nVidia GeForce 750M Graphics Card
15.4" LED Backlit 2880x1800 Retina Glossy Screen
95 Wh Integrated Battery