Compression is, IMO, one of if not the most useful FX for electric guitar. I don't leave home without it. After many years of using various 9V compressors, I recently graduated to the Black Finger real tube comp, and I really like it.
As to exactly what it will do for your setup, other than adding boatloads of sustain, the only way to really tell is to get one and play around with it.
I don't know anything firsthand about the model you reference, but looking at it, it doesn't look like a guitar toy, though. It may require a line level input signal, which you can only supply with a guitar rig if you have a FX loop on your amp, and you won't be controlling it with your foot.
I had a Boss compression/sustain stomp box, and I loved what I could do with it. Hit that last note of the solo and hold it till the end of the song if I wanted to. They do add to your sound, if it's tweeked just right. It can be overdone, though...
IMO, the best compressor is from the relatively new line of pedals by Line6. I believe it's called the Constrictor and is around $100-$120. It also happens to be the only good pedal out of that line - everything else stinks. But that compressor rocks!