I love my Surface Pro 4, it has great battery life and performance. One of my issue with the Surface is the cost of the Microsoft Surface Dock (£189 in the Microsoft Store and £130 on Amazon). The ICZI dock for the Surface only costs £79.99 on Amazon and does a similar job.
UPDATE: I tried to get it to plug into a Surface Pro 3 and its doesn’t fit, it seems the ports are 1mm to the left on the SP3 so the connector doesn’t fit.
The Surface Dock is specifically designed for the Surface 3,
Surface Pro 3 and Surface Pro 4 with a connector that plugs into the Surface USB 3 and Mini Display ports. The dock has 2 x USB 3.0 ports, 1 USB 2.0 port, 1 audio port, a Gigabit Ethernet port, HDMI and DisplayPort. It comes with its own power supply (5v) so your attached devices are not going to drain your Surface.
There are no drivers to install, it just plugs in and works. It’s a simple device that is really handy for Surface owners. Here is the dock in action: