I have a 60Cx, works great, and there are plenty of free street and topo maps out there…not always 100% accurate, but good enough for caching.
i like the fact that people stopped asking whether there are monthly fees for GPS service… progress.
If you still have them, check the packaging. Make sure they don’t say “heavy duty”, or barring that, make sure they aren’t yellow with blue trim. Those are not for high-drain electronic devices, and they aren’t alkaline batteries. The alkaline ones are black and silver.
Someone in the supply department might have gone with the less expensive option, thinking, “Batteries are batteries!”
Given that some phones now have actual GPS chips in them and don’t rely only on A-GPS, the main advantage of one of these really comes down to power - and how much of it you have when you’re out and about.
GPS uses A LOT of power and will deplete your phone battery pretty quickly. Then you’re kinda stuck while you go find your twigs to burn and recharge it with the Biolite (which is WAY cool, btw). The dedicated device runs for a few days and when the power starts to fade for them, pop in two AAs and off you go again for a few more days. Those AAs are going to be much lighter than the Biolite too…
Both your phone and a dedicated device are fairly close in accuracy so that’s a wash. And whatever other perceived advantages, besides ‘ruggedness’, a dedicated device has can be solved for a phone because there’s probably ‘an app for that’.
All that being said, I still lug my 60CSx (older model than these) out when I go off into the wilds (the phone comes too - but for communicating with the outside world while I’m gone)
A good friend of mine, and VERY active geocacher, has one of these (I still use my trusty old 60csx) and he’s never been happy with it. The rubber wore off the buttons quickly, the user interface is terribly clumsy, and the thing shuts down fairly often after which he must strip out the batteries and reinsert them before turning it back on or else it won’t come back on at all. And, yes, he keeps the firmware updated. After watching him fight this thing when we go out caching together, and hearing similar reports from other local cachers, I decided to stick with what I have and see if Garmin does betteron the next one.
If I were interested, I would self-assuredly get this. 
You have to calibrate the compass on this thing, otherwise you get the results you describe. Press the “menu” button while on the compass. There will be a calibrate option, which will walk you through some steps to calibrate. I usually do this at the start of a hike and it works fine after that.
Well let’s see here.
First, a dedicated unit like this will acquire a signal more quickly, in more places than your smartphone, and be generally more accurate than your smartphone (your GPS location will wander more with a smartphone).
Durability was mentioned, but for me battery life is important. A set of batteries will last me 10+ hours, and replacements will take up almost no room and space. My iphone might get 3-4 hours of heavy GPS usage out of it before it’s battery is dead.
My GPS is IPX7 waterproof, so if I slip and go into a river or creek my GPS should still work, while the iphone… err… won’t.
Let’s not forget that if you drop your phone and it shatters the screen, it’s actually way more expensive to replace (6-700 dollars) than your 300 dollar GPS unit.
Another big one is range/scale. Google maps tops out at around 1000 feet an inch for scale. My GPS goes down to I want to say 20-40 feet scale. That can be a big difference in topography.
And as for that stupid-ass kettle/charging thing that just came out, it’s nifty tech, but in reality they said it takes like 30 minutes to get a 10% charge.
This and the high end oregon units are not for day hikers. Hardcore geocachers see a lot of use from the added resolution and fix time, but generally speaking, you can find sub-200 dollar GPS units that replicate the benefits for a day hiker here without spending 400 bucks. My first geocache GPS unit was I think 120 bucks and the basemap was horrible, it had no compass unless you were moving at a brisk jog, and it was barely useable for geocaching without a dedicated compass. Still worked fine and I’d consider loading trail maps onto it for day hiking.