Wizards just announced that they're going to start playtesting and developing 5th edition D&D. And the interwebs are naturally on fire.

I was a playtester for 4e, and have loved it ever since it first arrived. Before that, I had enjoyed 3.5, a welcome refinement of 3.0, etc.

For me, and I imagine many gamers, the evolution from one edition to the next has been a story of steady improvement of the game experience.  That's not to say there are not problems, but every new edition of the game has made me happy, and there's no reason to think that a 5th edition wouldn't do the same thing. 

Fourth edition made some critically important changes to the game system that I think need to be retained for 5th edition. 

• Exceptions based design, with predictable math behind the system
• Easy reskinning and DM prep
• Concrete roles for classes
• Powers for all clases -- players always have a couple of choices to make on their turn, even at low levels

The areas where the edition seems to not have quite worked as well as it might are mostly non-combat related things.

• Magic Items -- I don't think they ever quite got the system right.
• Ritual Magic -- There needs to be a major redevelopment of the ritual magic system. I love the concept, but in practice it's incredibly rare to see rituals used. I would rewrite all rituals as skill challenges, and make a core body of those rituals available to all casters. 
• Skill Challenges -- Don't get me wrong, I love skill challenges, and I think they've finally reached a point where the rules presented work. But they've never quite been given the attention they need, I think. I think they're an important part of the new edition, but I think that if the system is going to focus more on RP and steal back a little emphasis from combat, the skill challenge system needs to be more fully developed.
• DDI - The current version of the DDI is okay.  The Character builder works, and I use that, but I find other tools (like power2ool.com) much better for creating monsters and building encounters, and Maptools is better than VTT. I appreciate that the open data API that allows tools like power2ools and the i4e app on my iPad to work, and think that needs to continue. I'd love to see an adventure builder or encounter builder -- one that lets you collect NPC stat blocks, treasure (including magic item cards), map builder, hazard and trap builder, etc. And along side it, a skill challenge builder for non-combat encounters. And once you have all that, make it possible to bundle and share that content with other DMs -- maybe with a rating system.  

Having said all that.... I'm completely mindful of the way I felt when they announced 4e -- I had a similar, meager list of changes that I wanted to see, and when they released the new edition it's changed were dramatic and sweeping in ways I had not imagined -- and most of them made me very happy.  So, I'm hoping once again that my grubby little list of ideas is blown away with the reality of the new version of the game.