There's a lot of discussion around smartphones vs. Garmins for long rides. In one corner, Garminados waffle about 15hr battery life, waterproofness and size, while in the geek corner Mobilistas tout cheap smartphones with a few extra batteries as the way to go, not doubling up on tech as the Garmin crowd carry mobiles anyway.
I present proof positive that a smartphone - even one 4 years old - can do the job. This screenshot is 5 1/2hrs into a 'ride', recording with Strava and using Viewranger for navigation, at 25% battery left. Critically the Viewranger Trip screen has been on all the time, with the nav arrow and other information displayed - meaning it can do a ride of over 7 hours with the display on permanently. Brightness was turned down, but it was still quite visible. Also the phone was connected to 3UK the whole time, mobile data and WiFi turned off.
Noting that if you set the screen to auto-off after say 15 seconds, you can wake it to check direction at an intersection, then it will go back to sleep automatically. This will dramatically improve battery life to about 12hrs in this case, as you see below screen power accounts for nearly half battery usage.
So you have Strava logging, always-on navigation, plus can receive calls/SMS. With the option to turn on mobile data to check email if really needed.
The phone in this case is a Sony Ericsson Xperia Arc, but for £40-ish you could have a Motorola Defy from eBay, rated IP67 waterproof and pretty shockproof to boot. Stem-mount it on £27-worth of Quadlock and you have a quarter-turn easy on-off solution that is weatherproof and can have its always-on runtime doubled to around 12hrs using £10 worth of extra battery. Or out to 24hrs if you have screen sleep enabled.
If/when you do need to stop and swap batteries, a Strava TCX/GPX file can be joined using one of a few methods to give that all-important one long ride.
The 4.4-star rated Viewranger app is free for Android and iOS. You can purchase Viewranger maps for less than half of the Garmin cost and the online route planning tool is genius. £90 gets you all of the UK (£199 from Garmin), or smaller bits are priced applicably less. Or you can download Openstreetmap / Opencyclemap tiles for free *from the app, on the mobile* and use them anywhere in the world. This can be done whilst on the road, no laptop needed - for example, using free Wifi in a café. Did this in Belgium last year- worked flawlessly.
Hopefully this goes some way to clearing the air and giving people hope that quality, robust on-bike long-ride nav, logging and comms is perfectly do-able for less than £100.