I have the Spider III 75 watt which has the same effect unit.
I really like it. The presets are pretty good, you can save you own patches so that's a plus.
Being modeling amp the hardware is pretty light compared to a tube amp, that's great for traveling. I can image the 120 being somewhat of a big amp.
I've played with a full band and it had the horsepower to cut through so you should have more than enough with the 120.
I'm looking to get the additional foot controller because it is very limiting live without any control.
For the price these are great amps and having the effects built in makes it a lot more enjoyable to go jam :) not much gear to carry around.