Hmmm, ok what you have looks like a nice start, but a few things:
1) You'll need to turn off the smoothing cos that will needlessly rocket your polycount up if you plan to keep it, and completely disguises what the ship actually looks like if you don't.
2) Geometry scale - since this is a fighter sized ship you definitely don't need to be modelling in tiny vents or tiny ribbing of any sort, and those modelled greebles are mostly too small to be visible in-game as well. Those parts can all be handled by normal map.
3) The struts on either side of the cockpit bulb are pretty iconic for the Seth, so I would definitely suggest enlarging them up to the same proportions as the original.
4) The Seth has 5 bulbus lumps with blue lights on the front end of them - 3 on top, 2 on the bottom. It looks like you've made the 3 on top into recesses with ribbing over them, which I find rather funny because that's not the first time those texture elements (they appear mostly on some FS1 era Vasudan ships) have been interpreted as recesses on HTL models, yet I just can't see them as being anything other than extruded oval domes with a recessed light at the front.
See the HTL Aten, Tauret or Horus for that interpretation.
5) The fins on the rear look like they've been built into the hull (and...changed shape) - but if you could make them attached by struts again, and then separate them from the rest of the model I reckon it'd be an awesome little feature to make them do something when the afterburners are engaged as the ones on the Horus do now. Probably having each one roll (Y axis) out of the way of the engine would work best.
6) Be a bit wary of the kinds of greebles you add where - not saying it's a problem yet, but if you add terran style greebles where there were previously only vasudan scales it risks significantly changing the look of the ship as a whole.
All that said, it looks like you have a very good eye for shape and form, so keep it up and I look forward to seeing where this goes!
