For the past 13 years I've been using a Garmin Etrex GPS device with a handlebar mount for my cycling. It's great, it takes AA batteries (spares are easy to carry); allows me to create routes on my PC and upload to the Etrex; Displays speed / average speed; allows me to upload my GPS tracks to Garmin Connect.
Why would I need another GPS device? It was a difficult decision. My cycling has stagnated over the past few months and I needed something to get me cycling again. Buying a Garmin Edge 200 was an excellent decision as it's got me cycling again.
All of my courses are now on Garmin Connect's web site. I can download a course to my Edge and cycle against a virtual cyclist. I can even download other people's courses and cycle against them "virtually".
The LCD resolution of the Edge has blown away the resolution on my ageing Etrex. The battery last for yonks - I've cycled for 1 hour and the battery is still at 100%.
The screen shows several different pages as your cycling. A map of your route (plus the virtual cyclist); a "side by side" view of the virtual cyclist and how far they are behind (or in front) in seconds / distance. It also has a stats page displaying speed (higher or lower than the average speed), average speed, total climb, time and distance cycled / remaining.
I used to use a Polar heart rate monitor and contemplated getting the Edge 500 (which has HR), but the chest strap are a pain to wear and they slide down to my (trim) belly. I'm glad I picked the Edge 200 instead.
The Garmin Connect site is one of the best tools for creating courses. I've previously used Memory Map, but the courses don't "stick" to the road. On Garmin Connect, the routes automatically stick. You can try Garmin connect without buying a device if you want to have a look.