Like said before before other posters, it depends on what you're wanting, or expecting.
I use to record my rides on my smartphone, (I still do really) but I wanted a bike computer so I could see numbers in real time, I tried a < £10 Aldi bike computer, but the magnet sensor died so I started looking for replacements and I thought if I'm going to spend £20 I might as well look a little higher for a better device (I think that may be a flawed cyclist logic tho) considered a Garmin 200 a worthwhile investment, easy to fit on the bike, easy to snap off, easy to upload ride data, as before I was using Endomondo to record the ride as I didn't like Strava for recording, but liked uploading my rides to Strava, Garmin has made this all a bit easier, so for me it's felt worth it. The 200 is very much a basic, entry level device though, but it holds it's price on
eBay second hand for around £50-60 pretty well last time I checked so it is able to recover a lot of the funds if you decide it's not for you.
Planning to use the breadcrumb trail for a map later on when it gets warmer, and I go further out, but as yet haven't tried it. With waypoints it's also meant to be able to give an alert for 'segments' if you're into Strava.