PMD portraits look really good but IMO the style of the actual dungeons can fall flat. Still looks good overall, but I think BW looks better personally.time-based mechanics were doable as a child (aside from honey trees since I wasn't allowed to play in the morning) but HGSS phone system was annoying even then.
HGSS is pretty much death by a thousand cuts. I like them a lot, but there are lots of small annoyances that add up overtime. Funnily enough some small changes would be able to fix most of it I believe.
I'm somewhat mixed on PMDs spritework actually...
Starters and pretty much all small Pokemon look great, but everything that is a bit bigger looks...messy. Bulbasaur to Deoxys had the problem of having to keep the GBA in mind (which also leads to messed up colors sometimes), but even some Gen 4 mons look...iffy, Empoleon is a good example.
Most of the bigger Legends do avoid this due to bigger sprites.
Also, Super Mystery Dungeon looks good, as the #1 SMD shill.