Excellent, drop-in replacement for the normal halogen bulbs. A couple of things worth noting before you buy.
First, they were longer than the halogen equivalents, so on my fitting they stick out from the shades a little. It's not that noticeable being that they're up on the kitchen ceiling & I have high ceilings in my house, but it may matter to you.
I didn't notice when I ordered that they are cool white. This makes them a pure white, possibly slightly blue, rather than the warm, slightly orangey glow you get from a halogen light. This seemed very strange at first & has taken a bit to get used to.
I'd also say that 50w equivalent is being a bit optimistic. They are certainly not as bright as the halogens I took out. This may be in part to them having a narrower beam angle.
Otherwise excellent, & I now feel very smug that I'm saving energy. My 4 light fittings in the kitchen & on the landing have gone from 200w to 16w.