IIR I had some acpi driver issue--in fact, had to manually white list my model in it--and power management is mediocre, even with powertop. But it gets the job done decently enough.
I too have a Lenovo x220. I use Jupiter [0] to manually send the computer to "power saving" mode. With that and the extended 9-cell battery, the screen only slightly dimmed, and wifi at full blast, I get around 7 hours of battery doing browsing and coding. I uninstalled Flash, and that gave me back around 2 hours of battery.
I have x220i and I needed to fix mic mute button [1] and add a power management script [2] for saving power while on battery. I still get some graphics corruption with gpu accelerated chrome but it's not too common and I can live with it.
It would be nice if Lenovo or Dell would check how well their laptops (or even some model) worked with linux and tried to get this kind of stuff as default on major distros.
It gets a little complicated. I got a Lenovo g560 with an Ath9k wireless card, and installed Fedora 14 on it and everything worked. I upgraded to Fedora 16 and everything worked except the wireless card. Apparently there is no way to tell the OS anymore that the wireless card is turned on. Filing bugs with Fedora and asking on the ath9k-devel email lists got no help at all.
What worked before no longer works. The card is permanently hardblocked. Supposedly the fix is to install Windows, flip the switch a few times, and then install Linux. I don't want it that badly. I will just figure out ndiswrapper.....
I know nothing about non-Thinkpad Lenovos and but with a quick googling I wouldn't put my money in one. As far as I'm concerned they might as well be Acer laptops.
When people say that Lenovo laptops work well with linux they mostly mean Thinkpad series and even then there are some exceptions. Best out-of-box experience will be with one that has intel cpu+intel wireless+intel gpu and was released a year ago. It's about as safe bet for a high quality fully working linux laptop as you can get.
IIR I had some acpi driver issue--in fact, had to manually white list my model in it--and power management is mediocre, even with powertop. But it gets the job done decently enough.