Low end WP s don't crash. I've had my 620 for over a year and a half, and have never experienced a crash. Moot point. 99% of the readers of this site disagree with you.
Depends on the application. I love browsing image sharing sites like 9GAG and Imgur.
The 9GAG app for the most part is a nice application, but occasionally playing a .gif would totally make my phone hang and/or crash.
Imgur has no official app, but it's third party client called Imgura is terrible. Opening a large image would always crash the app, the feed wouldn't show the latest photos.
Atmosphere Weather was an app that I saw featured on WPCentral, it would always crash on start up.
Even more annoying is the fact that when an Android app crashes, it simply crashes and you can proceed to opening it again or do something else.
But all hell breaks loose when a WP app crashes, the UI itself also reloads, making you wait more than a few seconds for your phone to actually reload the entire thing.
Tapatalk would reload the page each time I would post something, and if the message I was typing would be too long the phone would come extremely slow.
Not to mention that if you scroll too fast in myTube, or in the WPcentral comment section, or in the Whatsapp app the content in the screen completely dissapears.
And then I would often see the dreaded "resuming" message more often than not. I would even see it for apps I just left, such as Tapatalk.
And OMG it was such a pain switching tabs in Internet Explorer.
No phone is totally smooth in the low end side, Android and Windows Phone are pretty much equal.