I've added the following to my grub options (this helps a lot if you use Gnome3 like me): pcie_aspm=force i915.i915_enable_rc6=1 i915.i915_enable_fbc=1 i915.lvds_downclock=1
Which makes the complete entry look like:
title Arch Linux
root (hd0,0)
kernel /vmlinuz-linux root=/dev/sda5 ro pcie_aspm=force i915.i915_enable_rc6=1 i915.i915_enable_fbc=1 i915.lvds_downclock=1
initrd /initramfs-linux.img
I also use thinkfan to keep reasonable fan speeds along with the ondemand cpu-frequency scaling policy on battery power keep power usage down. I also minimize disk usage by taking advantage of my 8GB of memory and placing /tmp in tmpfs. These days I usually get 8-10 hours of actual use on a single charge, but most of that is writing/running code and browsing the web. If you usually do something more CPU taxing, you'll probably run closer to 5-7 hours. That's using the 9-cell battery that juts out from the case slightly and a low power SSD.
The most annoying part of the X220 is the buttonless clickpad. It works really well if you use the tap to click features, especially since the multi-touch lets you scroll around and double/triple click with multi-taps, but in the end I just couldn't get used to tap to click. Using the actual click/button, click and drag is so horribly broken with clickpads on Linux (and even Windows, if you ask me), that I gave up on that fairly quickly too. Finally I just disabled the touchpad in the BIOS. The touchpoint works too well to bother stressing over the ill-conceived touchpad on this model.
The IPS screen is great, but there is some occasional ghosting. It's only a temporary effect though, so it's a price I'll gladly pay for having a better image than any of the external monitors here in the house. It's also extremely bright, so I suggest turning down the brightness a few steps and letting your eyes adjust, otherwise you'll unknowingly burn your eyeballs out.
The battery also has a little bit of looseness when it's locked in. Based on what I've seen on other forums, this one's hit or miss, with some people having the same problem and many others not. Overall though, the laptop feels fairly solid without being heavy, but it's not nearly as solid as the X120e (which feels dependable) or the aluminum-body Macbooks.
Finally, the keyboard on this thing is great. The keys are nice and big, the escape key is prominent and in the right spot, and the quality of the tactile feedback is perfect.
If I had to choose all over again, I would've gotten an X220T, since I underestimated how much I use my wacom tablet, but other than that, I'm quite happy with the X220.