Things I like about RPGs:
-The ones I enjoy have big open worlds to explore.
-People to interact with are typically better than other genres.
-Developing a character style and personality such as it can be.
Things I really dislike about RPGs:
-RNG. A lot of RPGs are really random in terms of various skills.
*Disarming traps? Would rather there be a puzzle to disarm the various difficulties of trap for the first few times and then automatic.
*Combat skills. I like the feeling of my swing connecting actually meaning that my swing connected. Stats can scale up my character, but I like the main focus to be player skill.
*Diplomacy skills. Talking to people. It should either be based on skill level how convincing you are, with different results for different levels in the skill, or just a logic puzzle to figure out how it'll go.
-Shared combat skill and non-combat skill exp. You should get better at fighting by fighting, you should get better at talking by talking.
-Diplomacy skills in general. A lot of the time they're really poorly implemented and just a token thing. Neverwinter Nights (both 1 and 2) had Bluff, Intimidate, and Diplomacy sort of off to the side not doing anything. You could spend points in them, but they'd only really affect conversations that the map-maker decided to make them apply. It was arbitrary and tacked on and since, despite what some claim, those games were primarily combat focused they were essentially a trap.
-Skills that are traps. A lot of RPGs have at least a few of these. Skills that are like "Hey. I could be a smooth-talking bard and get my way out of trouble with my charming personality!" and it turns out it just means that you aren't going to do particularly well in the next forced fight.
-Morality systems. More common now than before, but eh. Still there. If they're going to implement these it should be more of an opinion+reputation system or a lot more shades of gray should be involved.
I definitely enjoyed Oblivion. While the characters and story were... Ehhh... at best, it got a lot of things right by me. Playing a sword and board character actually felt rather fun as I moved around blocking attacks, swinging my blade in certain ways to make the most of my Master in Blade abilities. That was fun!
Morrowind didn't really have the same deal. Though the magic was a -lot- more powerful (except the lack of mana regen without enchanted items), swordsmanship was really just hammer the attack button until the target falls over.
I really enjoy playing a character who is designed around keeping himself and his comrades safe and when the systems in place allow me to do that well I tend to have a good time. If the combat feels too random while I'm in it, I wonder if it was actually my lack of skill in the situation or just my luck running out.
Demon's Souls, from what I've seen, is exactly the sort of combat I'd enjoy. It could stand to have a more open world and a lot more story to it, but it actually looks to take skill to play and have your characters stats and skills affecting the combat without defining it.
...That was wordier than I thought it'd be. Anyway. That's essentially it.