I have bought a few things from Under Armour just for testing. My conclusion is that it is a highly advertised brand (but it doesn't come close to brands like Adidas, Nike, Columbia, or The North Face) and quite expensive for the quality of its products.

Quite cheap construction, the back support is almost non-existent and it does not fit a 15.6" laptop (only fits very small and thin ones, like notebook size). I was mainly disappointed with the very thin fabric and the lack of elegant storage spaces inside the main compartment. I would not recommend it, only for purely athletic use and not for much else.