Radeon HD 6790 is AMD's answer to NVIDIA's GTX 550 Ti. Both cards sit in the $150 segment which is key for budget gamers who don't want to shell out $200 for their card. HD 6790 delivers solid gaming performance for all resolution up to 1680x1050. 1920x1200 can work too, but depending on the game you might have to reduce the details setting.
When considering only current generation cards, the HD 6790 is clearly the superior choice. However, if you are willing to look at older cards then two additional contenders appear in form of AMD's HD 5770 and NVIDIA's GTX 460 768 MB. Even though it seems to lack some memory, GTX 460 768 MB can deliver 10% more performance at the same price of $149. AMD's HD 5770 comes at a lower price of $120 and is 13% slower. So depending on whether you are willing to go with last-gen, which is feature-wise pretty much the same, you could save a bit of money or get some extra performance.
Overall HD 6790 is a great card, but given the current situation around the $150 segment it can not shatter the other offerings there. If AMD can bring down its price by another $10 the situation would dramatically change, making HD 6790 the bread and butter card of the budget oriented gamer.