The free shipping was fast as usually, thanks to Amazon.com!
You can read all other reviews for its pros and cons. I'm just telling you why I've picked up this lens.
I went to a kid's party about two weeks ago, I took my K-x with the 18-55mm kit lens on it. I set ISO to 1600 (sometimes 3200) auto. I didn't use flash at all. Most of time, the indoor light were sufficient for a decent photo. However, kids moved a lot and fast, the shutter speed was simply not enough to capture those actions...so a faster lens is obviously necessary for this situation. I have a M 50mm f1.7 lens, I got the decent speed, but with manual focus, it's almost impossible to get focus quickly enough. So my conclusion is that I need a faster lens with AF!
I've been thinking to get FA 50mm f/1.4, but for indoors with limited space, its FOV seems too narrow, although its price is acceptable, I doubt its usefulness for indoor application (when I shot with 18-55mm lens, I seldom used any FL higher than 50mm, most of the time, 18-35mm).
The next thing I've been considering is this lens. Its price is right, it has f/2.4 aperture, it's lightweighted, it looks nice on my K-x (see those pictures I shot with my cell phone). I tested it as soon as I got it. Indoors, no lights on, only tv is on, so it's pretty dim, I set ISO to 1600 auto, lens wide open (f/2.4), AF worked well, pretty fast, no hunting, the picture came out bright, sharp, the color looks very good to me. I further tested in a restaurant (see those photos I uploaded). With K-x's low-light performance, this lens is a perfect companion! I would think it's more than enough for a kid's party (light condition is much better than restaurant). I cannot wait to put it in real test for the next kid's party coming soon...
Usefulness: although it can be used for anything, I would think it's most useful for indoors (specially for moving subjects that require decent shutter speed). For other situations, like outdoors, in good light condition, I still prefer using my 55-300mm (a very sharp, versatile lens to me), or the 18-55mm kit lens (I don't have any other expensive lenses).
Lens hood: it doesn't come with hood, I don't think you need a hood for indoors. I bought a lens hood on ebay for the old 50mm f/1.7 lens, but doesn't fit well. I put the hood on this lens, perfect fit! I can put the cap on the hood, too.
Thank you for your time, and hope this helps.
UPDATES:
After attending two birthday parties (one at school, the other at a friend's house), I would say this lens is sufficient for this purpose, although sometimes I only wish I got wider FOV (I killed FA 50mm F1.4 for this reason). Other than that, with aperture wide open, the picture is sharp, bright, color rendering is good, WB is accurate (more natural compare to my M 50mm F1.7 lens which gives me warmer tone). At both parties, I set my K-x to ISO1600 auto, at school I often got ISO800 at 1/60sec, in the house (in the afternoon, all natural light through windows except in the basement), I can get ISO-200 sometimes at 1/60sec, most of the time, I got 400-800, because of this, I switched my 55-300mm lens on for the second half for some candid photos.