After lurking for a few days, I actually signed up just to give my opinion on this subject.
My first impression was pretty negative, I saw an acquaintance of mine (who's not exactly a Pokemon genius) beat the first Gym without even trying too hard with an underleveled starter Eevee and a freshly-caught Bellsprout. I was convinced that this was going to be X/Y to the max - so unbelievably easy that you have to go miles out of your way to have anything remotely resembling a challenge. I was pretty sure then that I was just going to ignore the game.
Then I read some reviews and opinions online, and everyone was weirdly positive about the game. It was way more interesting and challenging than they had thought it would be, especially if you go for Pikachu instead of the OP Eevee. So I bought the game (Pikachu) anyway and I started playing. Although the first three Gyms were annoyingly easy - the first time I even used a Pokemon Center was in Lavender Town - the challenge quickly picked up from the Rock Tunnel onward. I never lost a battle, but I have been glad not to be running a Nuzlocke a couple of times, coming pretty close to a wipeout on several occasions. The fact that battles kind of play a second fiddle to catching Pokemon was a bit weird at first, but it sort of worked, at least for a change. In the end I beat the league, captured Mewtwo, filled the Dex (except for Mew, Meltan/Melmetal and the trade evolutions - the version exclusives came from PoGo), and that was that. Game over. I couldn't be bothered to do the Master trainers thing anymore.
In the end, I had a moderately fun time playing the game, but it left me extremely unfulfilled and hungry for an actually good Pokemon game with an actual postgame. The most baffling thing about LGP/E is that it's a game that is strictly inferior to the 14 year older FR/LG in every possible way except for graphics. FR/LG have the same region with the same Pokemon, but you get extra areas (Sevii Islands) with sidequests and new Pokemon, a better upgrade to the League, and there's the Trainer Tower (which is no Battle Frontier but still cooler than the Master trainers). It's also a bit more challenging and has a better battle system - LGP/E is focused only on direct damage, stat-ups, and status moves. That's it. There's just not a lot of strategical depth, even in the metagame, and so many moves are just completely missing from the game, as well as held items and abilities.
All in all, it's not the worst Pokemon game out there - X/Y still maintain that title - but it's close, and I really hope Gen 8 will change things for the better again.
Edit: There's one thing I forgot: LGP/E did succeed in rekindling my interest in Pokemon Go. That's at least something positive about it. :)