I've had incredibly good luck for the last several years with Linux on a laptop. You just have to be a bit careful. Here's what I've found:

- Backlight bugs are usually related to ACPI tables in the BIOS. Doing a BIOS upgrade will often fix them. This is especially true on the Thinkpad line where Lenovo explicitly supports Linux in its BIOS.

- Be careful with switchable graphics. While they have gotten a lot better, especially with open source drivers, they are still a pain (even on Windows). Choose a laptop with an Intel, or AMD APU. Or, barring that, make sure all of the scanouts are connected to the Intel card, like in my Thinkpad W540. The new Macbook Pro Retina 15" is exactly what you want to avoid - it forces all inputs to be connected to the discrete card when you boot Linux.

- Make sure you have a good wifi card. Intel or Atheros is the best.

- Do a bit of research before buying, like on the arch wiki.

- If you buy a bleeding edge laptop chipset, expect to need to use a bleeding edge distro for complete support.