The good things about the TI were the sound capabilities (it was one of the few home computers with a particularly musical sound) and the redefinable character set (great for displaying foreign language or other special characters on screen, as well as for games). Also, there were 16 colors available, and with a few limitations, they could all be displayed onscreen at once. (Certain combinations of text and background colors looked nicer than others on a TV, and these preferred combinations were listed in the documentation).
But the native BASIC language was slow, slow, slow, there was no really good way to write characters to arbitrary locations on the screen, there was no point-plotting mode available from BASIC. Also, the BASIC had no facility for directly accessing memory or running machine language programs (i.e. no PEEK, POKE, CALL or USR like most other personal computers). The Extended Basic and Mini Memory cartridges were quite an improvement.
The TI was a software backwater compared to the Apple, Atari and Commodore, but program trading groups like the "International TI Users Group" were helpful.
Extended BASIC ran quite a bit faster than plain old TI BASIC (although it was still rather slow in comparision to, say Applesoft or the other Microsoft BASIC's). But it did feature multiple statements per line, better screen, input and error handling, subprograms (great for structured programming) and speech synthesizer support. It also allowed machine language access (provided the memory expansion was installed). And while it did not provide pixel-based (rather than character based) graphics, there was one thing the TI had, that the other home computers didn't (or required a lot of programming to use well): SPRITES!
Sprites were little graphic characters that moved about the screen independently of the main program. Program statements could define what they looked like, how big they were, and where, when, and how fast they moved about the screen. Also, if any two sprites collided, it would be reported to the main program, which could then act on that collision (play sound effects, whatever). Of course, if the sprites moved too fast, BASIC might not have been able to keep up.
Another unique feature was the Speech Synthesizer. While not accessible from the native BASIC, Extended BASIC allowed access to about 250 words and phrases. The Terminal Emulator cartridge allowed the speaking of any arbitrary words or sentences; even the pitch of the voice could be changed. Of course both modules could not be used simultaneously,but in Extended BASIC, one could extract data from the Speech Synthesizer, manipulate it with string functions, and then send it back to the synthesizer. (There was also a disk based program that allowed access to the Terminal Emulator functions from Extended BASIC, but I didn't find out about it until much later). Of course, there was speech in some of the game cartridges too, most notably Parsec.
The Mini-Memory cartridge put machine language/assembly language programming and access to the hardware features of the TI, in the hands of those of us who though the 32K Memory Expansion was too expensive. It also provided a small amount (4K) of battery backed-up memory that could store programs or data.
Well, I packed up the TI and took it with me to college in 1983. Could I access the campus mainframes? Well, there was this little thing called a modem that was more or less out of my reach back then. How about computer science projects? Fine, but who used BASIC in class? (Most of the classes used Pascal, Fortran, or C).
Of course, there were always computer games. Parsec, and a couple of other games (a Dungeons and Dragons type game, and a Frogger clone, both written in Extended Basic) were real favorites on the dorm. I think I lost a keyboard, what with everyone coming in to play Parsec all the time....
Even though TI went out of the home computer business in October 1983, there was still quite a bit of support for the 99/4A, mostly in the form of local user groups. I was a member of the Pomona Valley TI users group between 1991 and 1994. By that time I had gotten a CorComp disk drive/ RS-232/32K memory unit, and was able to do more with the machine.
Most of the TI scene seems to have died down, with the last Fest West in 1998. But I still have my machine, and it gets occasional use. (I can still hear my dorm-mates saying, "How about a game of Parsec...")