The chip (limited by its 18 pin DIP packaging) had a single 8-bit bus and required a very large amount of external logic to support it. For example the 14-bit address, which could accesss 16K bytes of memory, needed to be latched by some of this logic in an external Memory Address Register (MAR). It could access 8 input ports and 24 output ports.
While a little slower (in terms of MIPs) than the 4-bit Intel 4004 and Intel 4040, the fact that it processed data 8-bits at a time and could access significantly more RAM actually gave it 3 to 4 times the true processing power of the 4-bit chips.
For controller and CRT terminal use this was an acceptable design, but it was too difficult to use for most other tasks. A few early computer designs were based on it, but most would use the later and greatly improved Intel 8080 instead.
wikipedia.org dumped 2003-03-17 with terodump