I owned a Nokia Lumia 920 with Windows Phone 8/8.1 on it for about 2 years. Prior to that, I had a Dell Venue Pro with Windows Phone 7. Both were "mid-to-high end" phones, so I can't comment much on your specific Lumia, though I do have some experience with a 520 and (if I remember correctly) a 635. The experience is not much different between high and low end phones except the touch technology, screen resolution and contrast ratios. (I do believe the hardware has more of an impact on performance with Windows 10 Mobile, though.)
Generally the "1st party" apps were pretty far behind or non-existent -- but you don't NEED them. There were excellent third party apps for things like Instagram and Foursquare. Windows 7 actually had really, really cool Facebook integration, but they did away with that in newer versions, so you get (basically) the same app experience as other mobile users.
The main software is really great (Windows 7/8) - things were smooth, fast and reliable. Data usage was reasonably light, and battery saving software worked well. Phone calls were reliable and clear. The calendar and email apps were very pleasant to use. The Word Flow keyboard (like Swype) was better than any Android keyboard I've found to date. The Nokia/HERE maps were pretty good, and the commute calculator was fun and useful. In general, your primary day-to-day usage of the phone was excellent...
... but you were always light years behind your Android and iOS users when it came to the latest apps. Words With Friends came out years later, and was poor performing. SnapChat has staged an eternal vendetta against Microsoft, and bars any kind of 3rd party apps from working. Banks are much less likely to have a compatible app, so I always looked a little jealously at friends that could use mobile deposit.
Of course, all of the above is "unnecessary luxury." I.P. Daley has excellent reasons for his recommendations, such as avoiding the data mining that Google relies on to pay their bills, and the aforementioned data/battery software. On the other hand, for my own uses, I find a reasonable budget Motorola Android device to give me more options and an overall better daily experience. (I actually spoil myself with a higher end model I got on ebay.) My recommendations are the ~$300 Moto X Pure, ~$200 Nexus 5 and Moto G 2015, with a sort of "maybe" for the Moto G4. It edges into pricier territory with a fingerprint sensor, and giving you minimal storage (16GB) at the entry level price - quickly ratcheting up in price if you want more storage. (Personally I use a Nexus 6 which is ~$200-225 on ebay, but I have large hands.)
If you can adapt to life without the apps, and just use your phone for calls, email, text, calendar, web browsing (IE mobile and Edge are reasonably good browsers - less of a delta than you'll find on a desktop) and the most popular apps (that are actually available for Windows 10 Mobile), you'll find you have a solid performing, reliable phone, and a great price. They are a solid buy, frugal, durable.
The Lumia 920 had a great camera for its time and was overall excellent hardware. I can't speak specifically to the Lumia devices that I.P. Daley recommends.