I have an Echo Dot that I have been testing and playing with.
The thing you have to realize, it is all in the cloud. The Echo is just a dumb box that translates everything for the Amazon cloud to work with.
Using it as an alarm clock - very bad idea! Here's why:
1) If there is a power failure, Echo has no battery backup.
2) Wouldn't matter if it did, if your network doesn't have battery backup too.
3) Which comes to the next point; even if power is OK, if your internet goes down - no alarm for you!
4) Lastly, something glitches in the cloud and no alarm for you.

For these reasons, using Echo for an alarm clock is a VERY bad idea. I have already experienced 2 of the above fails, in just the few weeks I've been testing.

An alarm clock is very important for most people. It is NOT something that should ever be delegated to the cloud.

I've got three dots in my house (love them, I bought one kicking and screaming and saying novelty the whole time but 2 days later I got two more) are you sure about the dot and alarm? I use mine daily for an alarm and it hasn't hiccuped once. I even had a power outage during a storm and woke up to power but network was down and I still got the alarm. It is a dumb box but it seems like amazon did give it some memory. FYI they are on sale for 40 bucks on Black Friday. I have it doing a lot of fun and cool things with my C4 system!