From: The Imperial Palace.
My favorite East Front game, too. The AI is better than that of WiTE. The AI is quite capable of encirclement and counter-encirclement; it defends objectives reasonably but also gives ground when it should. It does get a few bonuses on "Normal," but the playing field is level on "Easy." I like playing on Normal.
The officer system in Case Blue is my favorite innovation. Each officer gets a "deck" of cards and a pool of Command points. Every turn, the officer can play one card, if he has the Command to pay for it. The cards do things like boost morale, increase a unit's speed, improve a subordinate HQ's staff experience, help dig entrenchments, lead an attack, etc. Very cool.
I also agree that air is handled better in this game than in WiTE, where it was just too danged abstract. Here I feel like I have more control over my air units.
The UI might take a little getting used to. In my first game, I kept moving units accidentally, because I'd select "move" and then forget to unselect "move" before clicking on another hex. Also, you plot attacks by clicking the target first, choosing attack (or arty or air), then choosing offensive units to participate. It works fine, but it's not what I was used to from other games.
You mentioned not wanting to invest too much time. This game does ship with manageable short scenarios, and Vic has uploaded a third free short scenario. And other people are modding more such scenarios. That said, the longer scenarios are LONG. I'm playing the "Case Blue" campaign, 150 turns, and I'm on turn 4 after several days and many hours. It doesn't take as long to plot turn 1 as in War in the Pacific, but turns 2-4 weren't much quicker for me, whereas in WITP the later turns tend to move quicker (as things are already in motion). Anyway, for any of the long scenarios, this game would require a significant time investment.
Hope this helps.