First of all, kudos to the developers for giving us column of divisions and the British four-rank line, indicating that this isn't just the ACW in a shako and a more colourful uniform. There are, however, a few issues, but ones which I imagine wouldn't be too hard to fix.
Column and Line
One important aspect of arranging a Napoleonic brigade into column was to leave enough room between the component battalions to allow each to deploy into line without overlapping its neighbour(s). In SOWWL, however (and, I think, in the ACW titles), a brigade going into column of divisions has each of the columns rubbing shoulders with its neighbours. As a result, forming line involves each battalion marching to a new location (to make room), instead of just shaking out its companies into line. Note the lack of deployment room in this image.

Compare that with a formation where the battalions have been moved from line to column of divisions so that they're in the locations they should have been in from the start:

Single and Double Echelon
Line seems to be an exclusively double-echelon formation whereas a brigade forms column of divisions in a single echelon. Historically, brigades would form in whatever number of echelons their commanders saw fit, or according to doctrine, so it would be also possible to have this:

...or this (also available in checkerboard):

Some brigade formations during the period mixed line and column, so you might end up with something not unlike this:

Here's an Order Mixte:

There are too many possibilities to realistically expect the developers to be able to model, but please see my last point below for a possible solution.
Squares
Squares are nicely done, reflecting the practice of forming squares oblique to the line of defense, so as to maximise crossfire and minimise friendly fire:

Unfortunately, it seems to be very hard to keep units in square, even with cavalry in close proximity. They just can't wait to get back into line - even without the Prince of Orange around


This doesn't seem to happen all the time, though, as I tried a similar test while playing as Wellington in the full battle scenario, and the units came out of square facing the right way.
British Four-Rank Line
...but not in the four-rank line formation they started off in. Wellington's infantry used this formation at Waterloo in order to be able to form square more quickly (is this modeled?), but I don't see any way of using either the context or grog menus to get them back into that formation.
Skirmish Lines
A big round of applause to the developers here for including a very flexible means of deploying skirmishers that's quite different to the all-or-nothing aspect of skirmishers in SOWG. Ideally, this, among other things, should be restricted by unit type, quality and year, but that's for another day.
One problem I have with skirmishing as currently modeled is that the skirmish line doesn't move with the rest of the formation. For example, I took a brigade, created skirmish detachments (100 per line battalion, 200 per light) and pushed them out about 200 yards. Then I ordered the brigade forward. This is the result:

The brigade has pushed past the skirmishers and the skirmishers have turned at right-angles to their original facing, leaving a situation that can be fixed only by tedious micromanagement.
"Maintain Current Formation"(?)
One way to address this problem, and some of those outlined above, while also allowing players to experiment a bit with different (but historically plausible) tactics might be to include a "Maintain Current Formation" option, in the context and grog menus, i.e. after picking the desired location, the player would select "Maintain Current Formation" instead of one of the standard formations and off the brigade would go. Currently, the player can set up any desired brigade or divisional formation, but the work will be undone as soon as the next move command is issued.
Another change that would help this work, although I can only guess at what would be involved in implementing it, would be a period before each scenario starts during which the player can adjust formations and even positions of units rather than trying to do it while the battle is already under way. This might also allow some interesting experiments like sending the Old Guard to take Hougoumont.
