Win 10 hardware drivers still do not cover many of the brandname (frex Lenovo) laptop internals like network adapters, motherboard chipsets or integrated GPUs. This means that 'upgrading' to win 10 with a (Lenovo) laptop can result in total inability to connect to LAN or internet, no USB 3 standard functionality at all and lousy default video drivers instead of correct GPU drivers. In many cases correct Win 10 drivers are still not available from the brandname manufacturers websites either (like Lenovo) - And indeed, if one no longer has internet connectivity on the only computer system at hand that is now running Win 10, this does further complicate the search for the right drivers or workaround solutions.
As an example; I do know for sure from a firsthand experience (got to fix a friends laptop with Win10 problem recently - the solution was a clean reinstall of Win 8.1) that at least Lenovo Thinkpad Edge hardware drivers (year 2013 production model) are not yet covered by Win 10. I have no doubts at all that the same issues also concern many (perhaps even most) other special brandname laptop hardware device drivers.
As a result, I would not recommend installing/upgrading Win 10 on a laptop, unless you are one hundred percent certain that Win 10 has all of the necessary hardware drivers for your computers internals, or unless that specific laptop model comes with Win 10 installed. If you decide to try Win 10 on a laptop, do make sure that you have your previous OS installer disk/thumbdrive handy. It's better to be prepared for the worst case scenario here.
Personally, I am still happily using Win 7 64bit for everything, I have no valid reasons at all to upgrade into Win 10; IMHO the cons outweigh the pros on Win 10 upgrade even if it is supposedly a 'free' upgrade - Basically I'd be going from using a tried and true OS that currently works well into betatesting a new microsoft OS and potentially giving up what little online privacy I may have left in the bargain.. These days I take anything new from Microsoft (including windows updates) with a metric tonnage of salt grains. YMMV, of course.