It's generally the cheapest retro computer you can buy, and it's really weird, not some easy computer like the C64 or Atari 800:
The TI-99/4A BASIC interpreter is written in another byte-code interpreted language. This is because the BASIC ROM is not directly accessible to the CPU, you have to read it indirectly through a port. Likewise, the 16K of dedicated video RAM is also only accessible through a port. Now keep in mind this is a 16 KB computer, so your BASIC program is stored in the video RAM. It only has 256 bytes of 16-bit native RAM (unless you have the PEB...)
Now it uses a pretty good 16-bit CPU (but weird mind you- its registers are kept in external RAM), but massively crippled like this to keep the cost down, but also to prevent the home computer from competing with TI's minicomputer line. TI made millions of them.