I have a few Rosewill products. My keyboard is definitely my favorite (RK-9100, Blues) I really like the look of their new Throne case that they came out with recently. I have one of their cases that I used for a build, and I'm happy with it. At the time I got it, I went ahead and ordered the 750w power supply with it to power my graphics card. I've had it well over a year, and the power supply is just working fine.
I think Rosewill gets a lot of hate because they are newer to the market. Whereas their products were just kind of Newegg's generic before, now their products EASILY compare in terms of quality to other big names like thermaltake, corsair, coolermaster, antec, etc. Once they are more established in the communities, I think they will get less hate once people see how much they have improved. This sponsorship for Blizzcon will help that for sure. I mean, come on - if Blizzard trusts them to provide products for the expo, I think the haters should give them a second look.