[Forrest]

It really depends what you want to do. I love my 50/1.4, and I shoot it at f/1.4 a lot. It's got a bad reputation here, and if the focus is off even a hair, it lives up to it. But there's a hint of magic at full aperture, a dreamy look. If you're not going for that, it's maybe one strike against the more expensive version...?

Do you have any idea how often you hope to use the lens at any given aperture? The brighter one should in theory be sharper and contrastier at f/2, because it's already closed down a full stop. By f/2.8, it should be a lot harder to tell the difference. So unless you plan to use it wide open, or close to, most of the time, you probably won't appreciate the benefits a lot of people are paying for in the f/1.4 lens.

That said ... it's absolutely worth trading a zoom for a prime, especially if it doesn't cost much to try. You'll get a sharper lens with better contrast. ( Some people would dispute that, pointing to a lens with a comma in its price that compares to the $100 prime. ) You get a superb background blur when you want one, and a lot more control over it. And you get the opportunity to shoot flashless in a lot of situations that wouldn't be possible mor than a stop down at f/2.8 with a fairly expensive zoom. All these things together don't necessarily mean you'll love yours, but it's easier to get it wrong with a 50/1.8 than a 200/2!