I couldn't find a review thread, so I'll post this here... I helped my buddies over Ultra N Podcast, producing the review (I've played the games and wrote the script. Daniel is narrating it) PT-BR content 🇧🇷
In summary, the games themselves weren't much changed from what I could gather (I never played the originals myself, but I looked up to make direct comparisons); But they did add some features like Fast Forward (that speed up the whole game, by the way), High Definition dialogue boxes and there's a remastered soundtrack option for Monster Rancher 2 (not on 1 tho, strangely); --My gripes will remain on the lack of displaying options, with no chance to disable the borders;
Otherwise, the games are exactly like you remember. With the CD summoning feature included; There's a robust searching option, so you can find pretty much every PS1 game, lots of Music CDs (including some newer ones), a whole bunch of SEGA Saturn games and even the whole Switch library seems to be present. Of course, you can also generate a random code to summon monsters, if you want to.
I think it's a good deal, especially because this CD gimmick thing is preserved somewhat and that's important; The amount of enjoyment you take from the core games comes from if you really enjoy pet simulators (more than battleling). 🐾