tl;dr: don't believe it, at least not for any recent Intel ThinkPads.
Counterpoint: I chose the ThinkPad X220 because it was on that list and it works (nearly) flawlessly under Linux. The only problem I know of is that the mic mute button doesn't work. That's it.
Which distribution of Linux? Do you use compositing? If so, what compositing window manager are you using? What's your typical uptime? Do you use multi-monitor? Have you used an 802.11n AP, particularly a 5GHz AP supporting WLAN power save (such as an AirPort Extreme)?
Under a different set of circumstances, Natty could have been said to be flawless on my T420, and indeed I thought it was for the first few days. When I started using the system more intensively for the tasks I bought it for, I began to notice the problems.
- Distro: Ubuntu, then Fedora
- Compositing: Yes
- WM: Mutter
- Uptime: weeks, currently 15 days
- Multi-monitor: haven't yet, I could try and let you know what happens
- 802.11n: No
I noticed on the notes for your laptop that you have an Nvidia graphics card. I had an Nvidia on my last laptop and that experience convinced me never to get a card that requires a proprietary driver. I always had issues with compositing, resuming from sleep, and artifacts appearing on my desktop (especially text corruption in terminals).
Unless you were naive enough to buy the X220 with the "Thinkpad b/g/n"[1] wireless option. Then, grief, anger, acceptance/resignation (in the form of a USB wireless stick[2]).
There is a host of other issues, but nothing that can't be worked around after hours of researching blog posts and manuals. More kernel panics on suspend (related to the aforementioned USB wireless), external monitor issues, USB 3 port disappearing ... You know, small stuff.
[1] RTL8188CE 802.11b/g/n WiFi Adapter (in my case, anyway)
Counterpoint: I chose the ThinkPad X220 because it was on that list and it works (nearly) flawlessly under Linux. The only problem I know of is that the mic mute button doesn't work. That's it.