I'm a huge fan of both, but you're not the first person I've heard who had problems with the writing style / dialogue / characterization of Fire. In that respect, I'm not sure Deepness will feel different. Vinge has a pretty consistent style and cultural stance, which IMO is an interesting balance of Heinlein-style techno-libertarianism and genuine "humanism" (which extends to dogs, plants, and other thinking creatures).

Structurally, though, it's pretty different. The characters have much more opportunity to develop, and it's purely hard sci-fi where Fire used its setting to veer into fantasy ideas. So my biased advice remains: give it a shot :)