Honestly, no. While Base 81 Speed is not awful, there are a lot of faster Pokemon out there, not just that you'd be facing, but there are other speedy water type sweepers out there, such as Starmie (Suggested), Sharpedo, Gyarados, Rotom-W, etc. If you want to sweep with Milotic, make it bulky, as it has all the stats of a great tank/bulky sweeper. Recover will be a must. If you want a fast water sweeper, go for Starmie, which has same amount od SAtk, but the ability to outspeed most other Pokemon when at max speed, while packing a large punch with it's amazing movepool.
If you want a bulky but slow sweeper: Go for max HP max SAtk Milotic
If you want a fast coverage sweeper: Go for max Spd max SAtk Starmie (Timid)