I've just finished a game of Halle (solo vs myself, so no FOW). Here is the final result:

The Prussians had the option of moving earlier then I expected, so I decided to move them into the town rather than having them standing around being picked off by French skirmishers as happened historically. This resulted in confused and bloody fighting in Halle itself, but the French were able to hang on to their gains.
Having three bridges to cross and over an extremely narrow frontage make this battle look like it will be a real slog, but it turned out to be very enjoyable scenario.
Some things I would consider changing if I was going to play it again:
1. Improved command rating for Bernadotte, and possibly fanatical morale for his corps. Bernadotte was very motivated after his no-shows the 14th, and it's probably safe to assume that the corps itself was getting some stick from the rest of the army over it, so they had something to prove.
2. Increase game length. The historical battle seems to have lasted about 2 hours longer than the scenario in the game.
3. Change the victory conditions to de-emphasise possession of Halle itself and instead stress the destruction of the Prussian reserve corps.
4. Delay activation of the Prussian main body.