Updated: July 12, 2017
In my long history as a distro tester, I've only tried pure Debian twice, version 5 in 2010, and then version 6 (Squeeze) in 2011. The former was an okay exercise, somewhat similar to my early endeavors with CentOS. The latter was an absolute flop. In both case, the network side of things was terrible, but it was a dealbreaker the second time around.
Fast forward to 2017, I am inclined to say Debian is a great foundation, like a great recipe, but a recipe and a tasty cake are two different things. If you're wondering, then by this analogy Arch Linux is harvesting your own corn and milking your own cow. Anyway, my tolerance levels for un-PnP features of the Linux desktop have dropped significantly, and so I was reluctant to try Debian. But a new version is out. Let's give it a try.
Cinnamon version
I decided to begin my testing with the Cinnamon flavor. Apart from Mint, I haven't tested this desktop environment much lately, and I wanted to see how it works on other distros, too. Live edition, begin boot. No problems with Lenovo G50 & UEFI, although you do get an ugly double beep before the GRUB menu loads.
Eventually, the desktop loaded. It ain't a pretty thing. The icons are horrible. The system area looks out of place with that over-sized Bluetooth icon. It sure isn't inviting in its naked, unpolished form.
Network connectivity
And here my problems started in earnest. I did notice the desktop was kind of sluggish, but it was only when I tried to connect to my Wireless router to actually begin the testing session that I realized how bad it was. It took almost two minutes for the password prompt to show. The system never established a connection to the access point.
I then tried to disable and re-enabled the Wireless, and after this, I never again got the list of access point, and never got a chance to establish a network connection. Top that with 1999-era aesthetics, and I wasn't in a good mood. This was a third time in a row that Debian was not playing ball with my network devices. I'm sure someone will tell me how I'm missing an important piece of ideology or something. Or find a reason why I'm at fault here, of course.
Other observations
While doing my brief test, I tried to rename a file in the file manager - it never shows the position of the mouse cursor, or gives any indication the text is selected. Quite annoying. I had to restart Cinnamon two times, because nothing really worked, induced by the very high CPU usage. All in all, in between breaking the laptop to pieces and ending this nonsense, I chose to reboot.
Gnome attempt
I thought, maybe it's the Cinnamon version. So I tried the Gnome one. Double beep, and then the system started booting. A text boot. No nice splash. I noticed all sorts of error messages related to the Realtek firmware as well as a nice little crash. Lovely.
...
bluetooth hci0: Direct firmware load for rtl_bt/rtl8723b_fw.bin failed with error -2
Bluetooth: hci0: Failed to load rtl_bt/rtl8723b_fw.bin
rtl8723be: Using firmware rtlwifi/rtl8723befw.bin
rtl8723be 0000:02:00.0: firmware: failed to load rtlwifi/rtl8723befw.bin (-2)
rtl8723be 0000:02:00.0: Direct firmware load for rtlwifi/rtl8723befw.bin failed with error -2
...
...
Task dump for CPU 0:
NetworkManager R running task 0 782 1 0x00000008
ffffffff97113540 ffffffff964a3bbb 0000000000000000 ffffffff97113540
ffffffff9657a4a6 ffff89bb4f218fc0 ffffffff9704a6c0 0000000000000000
ffffffff97113540 00000000ffffffff ffffffff964dedf4 0000000000000001
Call Trace:
<IRQ>
[<ffffffff964a3bbb>] ? sched_show_task+0xcb/0x130
[<ffffffff9657a4a6>] ? rcu_dump_cpu_stacks+0x92/0xb2
...
The desktop eventually loaded. Simple, stock Gnome. Ugly, lo-res icons. Nothing exciting or useful at this point. And slow and syrupy, because, you guessed it, we were having network-related problems.
Like Cinnamon, the desktop was utterly sluggish. The system load was around 6 or higher, and the WPA supplicant - and the network manager - were using 100% of the CPU. Much like the other test, I was not able to connect to my router. It would take anywhere between 60 and 120 seconds for the password prompt to show, and then for the connection attempt to fail. Everything else also lagged, because of that.
I tried reloading the module into the memory, including some tweaks, no help. I tried to restart the network manager, no luck. I tried using the ifconfig command, only to find out that it has been deprecated. Yes, Captain Obvious, play along, will you.
Reading online, I found a Debian mailing list announcement that explains the decision to remove this command. This isn't related to the review, but it further highlights the deep, deep stagnation in the Linux space. Paraphrasing: The command doesn't support modern features, and it has not received much love ... What. Then fix it. Difficult to use in automation ... Except the wider enterprise industry that actually powers the world. Indeed, indeed.
When I see things like this, things like the Gnome desktop environment, systemd, and all these other self-justifying tools and ideas and decisions that are based on whim and dubious arguments, it's no wonder that Linux desktop is becoming less and less relevant every day. Worse than that, it's sapping away energy and loyalty from people who genuinely love and believe in Linux.
Wait, you're not being fair, CentOS also ...
If you've read my CentOS articles - and there's a whole bunch of them - tested on this same laptop, you will notice that this distribution also has problems with the network. True. But it didn't have the proprietary firmware to begin with. Once I've supplied it, the network was up and running. We're talking kernel 3.X versus this brand-new kernel 4.9. Moreover, as you're familiar with my Realtek woes on the Lenovo G50 laptop, you also know that the issues have been resolved with kernels 4.8.7 and above, so there's no reason whatsoever for this pointless, moral-sapping fiasco that was affecting me. Recent releases of Kubuntu and Manjaro both work splendidly with the Realtek card. This is some sort of regression, and it's specific to Debian and Debian only.
Debian comes with the right firmware - and a broken implementation. This is in conflict and contrast to my previous findings on a dozen other Debian-based distributions over the past couple of years. Debian comes with a modern kernel and yet, it has a network implementation that is years behind the market. So maybe CentOS started with problems, but after I had the module loaded, and even better, once I used my tweak for the Realtek card, it was dandy. Therein lies the difference. If I can't make basic progress in the live session, there's no point doing much else. This happened with Squeeze and it happened against with Stretch, six years apart. Awful.
Conclusion
Debian 9 Stretch is a horrible disappointment. It's a completely unusable product in my scenario, and I see no real reason why I should bother using it. Ubuntu and friends offer a superior experience. Perhaps Debian serves a purposes somewhere, but I fail to see it. What really irks me is that in six or so years since I've last tried it, it's as if nothing at all has changed. Exactly the same kind of issues, only different hardware and kernel modules.
Perhaps without Debian we wouldn't have Ubuntu and such. For that matter, we also wouldn't have pyramids without slaves. But that does not mean we should be grateful for slavery in giving us big stony architecture. Similarly, Debian may be a baseline for many other distributions. But on its own, without a thick layer of customization and changes, it fails horribly on the desktop. This test makes me sad and angry. Because I know an end when I see one. It's still a few years away, but it will inevitably come. Anyway, completely not recommended. My last venture into Debian this way. We're done.
Cheers.