I really like the MW longsword...it becomes a 99 speed (used to be 100 speed before nerf) weapon with dmg similar to a stock sword of war.
Its shorter though, definitely have to use footwork & manual block a good bit to make it effective.
Sometimes the short length can be a challenge, but honestly with 6PS+ and a MW longsword you can deliver pretty lethal blows against all but high armor/strength builds...and like mentioned - the speed is incredible (faster than all but katana which hits like featherduster)
For background, I use 18 str 21 agi build...with 6 PS, 7 Athletics (footwork), 7 WP (164 2hnded skill), and then a couple in ironflesh when using the MW longsword.
The short length has one benefit - less likely to get stuck on things when fighting in tight areas or around lots of people. If you are good with attacks and pretty good at parrying, you can do well with this weapon...