Ahh mystery dungeon. What an awesome series. I'm not super familiar with the category of rogue-like games, but I must say that Pokemon really fits the genre well. I think the first two entries in the series are really solid games and would highly recommend them to anyone who has yet to play them but is interested in the series.
I think what the mystery dungeon world is so good at doing is creating an amazing world with characters that you can really get to know and care about. I don't it's necessarily fair to criticize the main pokemon games for being not as good at this because of the fact that the game itself is a lot different, but I think it's truthful to claim that mystery dungeon does an amazing job at presenting stories that you can really get into, with characters that you can't help but become attached too. The first two games were really good at this I felt - both did so in different ways, with the first game feeling more "open" in the sense that you as the player got to build your own rescue team with your partner and go from there. Explorers really shined in integrating you more so with other characters - the guild was a really great way I thought to introduce more characters and allowed them to create what I think many people feel is the best plot of the series. In any case, at least for the first two games, it was basically impossible to put the games down. And even after you finished the main story, there was just so much to do and explore.
The series itself is kinda in a weird state though. The rescue team games were such a good initial entry and Explorers did a great job on expanding on that base in terms of the mechanics. But it seems like gates took a step back from that and even SMD doesn't seem to be as heralded as the first two? That said, I'm wondering what people's thoughts are on Gates to Infinity? Honestly, it was a game that pretty much slid under the radar for me, considering I didn't hear much hype about it and a lot of the reviews were pretty negative (in comparison to the previous 2). That said, I feel like I won't mind some of the changes (such as party EXP - leveling mons up was such a pain). My sister has SMD and it seemed to me to be sorta underwhelming, although not necessarily bad. I agree with a lot of Megazard's points on the game, even having not played it. It's weird that in terms of game mechanics, it almost feels like they've gone backwards. Explorers did a good job at expanding stuff, but then they took a lot of the complexity away after that for whatever reason.
The only thing I really hate about the overall series? Goddamn traps and monster houses. Those things scare the shit out of me. I know I'm just a big puss, but man, younger me those things scared me way too bad. It's not even like they were too hard for me or anything, it's just I've never liked sudden scares. I'm interested in buying gates, so if I do buy it, I guess it'll be an opportunity to redeem myself and fight my fear haha...