Pros: Overclocks as well as most other x6s
Cons: Locked multi means ideally you want to use DDR3-1600 and a mobo good for ref clock OC
The 1055T, in my experience, oevrclocks as well as most of the other Phenom II x6 processors, provided you have the proper hardware.
Remember, this is a locked multiplier processor, so ensure you have the proper equipment. That is: a motherboard with good ref clock overclocking ability, and at least DDR3-1600 for your memory (to reach 4GHz, one ideally uses a 286-300Mhz bus clock at which you can use the x5.33 multiplier to set DDR3-1600 optimally).
My 1055T has reached 4GHz with 1.4V under a Noctua NH-D14 (better cooling can equal lower volts). Results may vary; some are better, some are worse. There is really no way to tell.
As always, make sure your motherboard supports the TDP of the 1055T you have (95W or 125W).