I think you'll hear good and bad things about any product. I had heard amazing things about the Theo, but the one I got must have been a lemon because after a year, it stopped working properly and tried to boil my fish. Now, on the other hand, I have heard horrible things about Top Fin heaters, but I was in a pinch and needed two heaters, so I picked a couple up. They have been working great for the past month and a half. :)
I'd be willing to get another Hydor, since mine worked awesomely for the first year, but I'd always be paranoid about it shooting the tank temp up like mine did.