(1) No Jim Cameron
(2) it was missing the most integral parts of the first 2 previous movies- T1 being essentially a love story between Sarah and Reese, and T2 the love of Sarah for John, and more importantly the idea of man vs machine. None of this was in T3. It had no 'heart' I guess, just an empty shell of a movie with 2 returning actors and some newer digital effects thrown in for the sake of it.
(3) No Terminator theme! That theme song is one of the most memorable parts of the first 2 films.
(4) The T-X. Give me a break. What a gimmic, the purpose of this was to get 12 year old boys into the theatre to check out her t*ts. "Thanks for the $$$ boys, enjoy the film".
(5) A boring as hell script.
T4 will suck for pretty much all of the above. There's my 2 cents.