Speaking of PDM, I've really hated PSMD, the only Pokemon game I've really disliked btw.
First of all the difficulty isn't well balanced. The game is either nearly impossible or too easy. For example, in my first playthrough, when I had Mudkip and Tepig, I got one shot by Heliolisk and its Thunder or Hyper Voice, in an early-game dungeon. And even when I arrived to the bosses, they were impossible to pass for me because they are Poliwrath and they resist to Fire and have Water Absorb, and the non-stabbed attacks were way too weak. And I say my first playthrough because yeah, I was forced to restart a new one with two other Pokemon.
And that's not the only time I got blocked this way. Of course I could train my mons and gain some experience, trying and retrying again and again until I beat the boss. But the problem is when you lost in a dungeon, you roll back to the last save, so you lose all your experience you gained. I've personally stopped playing after the Voidlands, since my Pokemon weren't trained and strong enough and probably never be. There were moments where I was thinking "Damn, this game is so mean !"
Speaking of the Voidlands, maybe that's just because of my frustration about this game, but I found this scenario part unnessecary long. They were several moments where I was thinking "Damn we're still there ? All right, that's enough !"
On the other hand, dungeons become way too easy when you have level 50 Alakazam or Tyranitar when you're not it the middle of the scenario. Because yeah, the other problem I have with this game is it's recruitment system. Besides the fact that you don't have anymore that chill after being nearly to beat a Pokemon you want to have and thinking whether it will join your team, because it's now 100% guaranteed the Pokemon you help will do it, helping it will connect it to other Pokemon, which will also join you. And some of them are overpowered when you've just finished the first part of the scenario, like the two I mentioned.
I've also HATED the partner. It's behaviour is so childish and annoying. I think I've never hated that much a fictional character before.
All this to say I've never finished that game and I never plan to do neither.