The Kaiser class were the first German dreadnoughts to mount superfiring turrets, on the stern even. This matters. The Friedrich der Grosse was Hipper's flagship at Jutland, and has her own special place in history.
or the more traditional stern gun haymaker and bow sidemount,
or other variations on the theme. Plus, with 4.5 units, that can be a 75 round haymaker in X turret. It's all goodness.
Kaiser is still a 28 second ship, and with the same three shaft arrangement will have less acceleration compared to a four shaft ship.
However, the same triple shaft and twin rudder arrangment will also result in excellent maneuverability. I know, this is probably sounding redundant, but when it gets down to it, all of the German Dreadnoughts have pretty much the best maneuverability in the hobby.
The Kaiser is again, longer and larger than the Helgoland, and additionally has the first raised forecastle in the series, so there's a bit more to shoot at there. Just a bit.
Again, given the relatively simple gun arrangement, and somewhat generous hull size, the Kaiser class should be fairly friendly to the beginner. This is offset, however, by the lack of an available kit. With the two haymaker and stern gun arrangement, she should be wicked in hands of an experienced captain, with the sole exception being (again) the lack of speed.
I'd love to have a Kaiser class battleship, if only for the looks and history. I even have a set of plans set aside for ... contingencies. I think that if a kit were offered, I would definitely recommend her as a good first or second battleship for an Axis battler, or for someone who wants something (relatively) lightwight to have some fun with. Given the available armament combinations and firepower, I think that she could be devastating and a definite tactical asset.