I actually enjoy the Natascha in some situations. It was my first strange, so I suppose there's some sentimental value attached to it. Honestly, it holds chokes much better on defense than the stock mini. The slowdown is an absolute killer enemy pushes (and retreats). Natascha works great in conjunction with the Kritzkrieg as well, in my experience. The slower rev up time is torture. The weapon works great as a team weapon; you're not going to get as many frags as you would with the normal mini, but more often than not, (if your team is with you), the enemy will take a larger loss as their players are currently swimming through molasses as rollers, stickies, rockets and more pick them off.
TL;DR
It's a fun weapon to use, but obviously stock mini is the best overall.