The specification has multi-station throughput of at least 1 gigabit per second and single-link throughput of at least 500 megabits per second (500 Mbit/s).
This is accomplished by extending the air-interface concepts embraced by 802.11n: wider RF bandwidth (up to 160 MHz), more MIMO spatial streams (up to eight), downlink multi-user MIMO (up to four clients), and high-density modulation (up to 256-QAM).
The 802.11ac second wave is more mature. With improved hardware, 802.11ac moves up to the 5 GHz band where it can offer mandatory 80 MHz and optional 160 MHz channels.
802.11ac beam forming is a big improvement which will improve throughput with multiple access points service an office etc. Unfortunately many non-compliant 802.11n devices do not properly support beam forming.
Using multiple antennas and borrowing from phased array radar technology will improve performance for each user in a coffee shop. The multiple antennas electronically steer the beams. This gives each user more bandwidth that is possible with 802.11n.
A mobile phone with 1T1R will achieve 433 megabits per second. A 2T2R can achieve 867 megabits per second. This assumes that the access point has the capability. Many places still use older 802.11n hardware.
Clearly up at 5 Ghz there is a lot more bandwidth. The span for 20 MHz channels is vast which is why we strongly recommend abandoning 2.4 Ghz completely. 802.11a, 802.11n and 802.11ac and above all support 5 Ghz. There are many dozens of available channels and with automatic channel selection there is lots of room for minimizing overlap and interference.
VHT 2.4 GHz
We have seen several 802.11ac devices with VHT 2.4 Ghz which should be disabled. Basically its a gimmick by vendors to make claims that their products are faster than their competitors. By using the ISM 2.4 Ghz band the vendors try to use it for more performance.