the lovely people at classicshell.net have their alternative Start Button all ready for Windows 10 users -
http://www.classicshell.net/If you're running an older laptop / desktop check that you're graphics drivers are compatible and are available to download and install before 'upgrading' to Win 10.
It's also worth checking older devices such as scanners and printers etc to ensure drivers are available for Windows 10 (especially if you have an older HP printer).
First few impressions are that Chrome is a fair bit slower starting up and in it's general usage - as is the Windows Search function. Doesn't seem to have the 'snap' (responsiveness) it did when running Windows 7.
I'll still wait a month or two before considering upgrading from Win 7 to Win 10 on my main machine - let those bugs and kinks get worked out first.