For some time I have been interested in setting up a development VMWare ESXi server on a laptop to help with testing etc. The problem in the past has been that the ESXi install only comes with drivers for high end network cards and the process of adding the required drivers is chewy
As of ESXi 5.5 update 3 and ESXi 6 the drivers for the Intel 82579LM network card have been included in the core product  so as long as your laptop has > 4GB installed ( 4GB is not enough as it registers as 3.9 GB and the install fails ) you can install ESXi 5.5 or 6 on your laptop.  I only found this out after doing all the chewy stuff first 🙂
The only other serious issue that I have found is that when you are creating hard disks they must be IDE drives and not SCSI drives otherwise they will not be visible to the guest Bios.
There is a bit of a niggly issue with VSphere whereby the console does not always display. Richt clicking on the menu selecting the pop up console seems to free this up.
ESXi is free for up to two physical CPUs