Some better dialogue, some better storylines. Aside from clone-centric episodes, TCW is really lacking in these departments.
Overall I think Season I and II had the best mix of action, dialogue, and story. Sure they were lacking a bit in the visual diversity and intensity, but somehwere in Season III the story seemed to slip in favor of fancy effects and "homages" (C'mon, we've had Alien, Godzilla, Seven Samurai, Jaws, Ninjas, Gulliver's Travels, Alice in Wonderland) It's like the team is having trouble coming up with original stuff.
Remember Trespass? That, along with Rookies, The Deserter and a few others is one of the best episodes of the series. You had a cool setting, cool aliens, political stuff that made sense, evil guys, good guys, action, a major protagonist (Chuchi) that wasn't part of the "Big Three" (Ahsoka, Anakin, Obi). And the conflict that was showcased as unnecessary and unfortunate, but unavoidable. Clones were ordered to kill the Talz, and even though you as the viewer knew it was wrong they did it anyway. Plus Rex had some awesome moments, and the Jedi actually negotiated like they were supposed to instead of just swinging a glowing baseball bat around.
If you haven't watched Trespass in a while, go ahead and re-watch it during TCW's hiatus. You'll see what I'm talking about. Season 1, episode 15.
On a related note, what in your guys' opinion are the best episodes of TCW? I'll list some of mine:
[spoiler]Season 1: Malevolence Trilogy, Droids Duology - Downfall and Duel, Rookies, Cloak of Darkness, Lair of Grievous, Jedi Crash and Defenders of Peace, Ryloth Trilogy, Hostage Crisis (Total: 13)
Season 2: Holocron Trilogy, Geonosis Quadrology, Grievous Intrigue and The Deserter, Lightsaber Lost, The Mandalore Trilogy (Say what you want, I liked how they handled Mandalore), Cat and Mouse, Bounty Hunters, Zillo Beast Duology, Fett Trilogy (Total: 20 - As you can see, in my opinion Season 2 was pretty dang awesome)
Season 3: Clone Cadets (I didn't really like ARC troopers), Hunt for Ziro, Heroes on Both Sides, Nightsisters Trilogy, Citadel Trilogy (even though Echo died), and the Trandoshan duology (Total: 11 - as you can see, much less good here. Not really sure if I like the Mortis trilogy or not, cool at some points, bizarre and needless at others)
Season 4: Calamari Trilogy, Umbara Quadrology, Deception quadrology (Total: 11) [/spoiler]
Another thing I really, really really want TCW to do is have some more interconnectivity within the whole show. So far there have been some huge revelations and mind-boggling events (Krell for instance) that the show just doesn't follow up on, or just doesn't acknowledge (Echo, Waxer). Hopefully the establishment of some of these big plots (Mandalore, Savage and Maul) where the issues are still left unresolved will allow this interconnectivity to happen. One can only hope.