Since moving on from IBM, I've been using a Lenovo E540 that I picked up fairly cheap, and naturally I run Linux on it. Being a Debian nut that Linux is of course Debian Sid.
I compile my own kernel tailored for the hardware about once a week from the linux-stable git tree and so far haven't had any real issues. I've noticed the card reader doesn't seem to work but haven't put a lot of time into fixing it. There does seem to be a driver in my current kernel (3.16.1) but I haven't added it to my kernel config, yet. Linux compatibility and performance has been great. The only upgrade I've made is adding a Samsung 840 series SSD.
I did however want to write this post to warn anyone having suspend to ram issues on this laptop to stick to UEFI verison 2.06 or lower. I upgraded last week and suddenly my laptop would not longer fully suspend. The power LED would slowly pulse, but I could hear the fans still going if I'd been taxing the CPU prior to suspend. Resume would definitely not happen.
The solution of course is to downgrade back to a working UEFI version if you've upgraded and are facing this issue. I should also mention that I tried loads of difference ACPI configuration flags on the kernel commandline and none of them seemed to help. It all comes down to a change in the UEFI code in version 2.07.
Link to the working (for me) BIOS (version 1.61) for the E540 is here, as Lenovo has taken it off their main download site: http://download.lenovo.com/ibmdl/pub/pc/pccbbs/mobiles/j9uj09wd.iso