I don't have a lot of history with Epcot, the last time I went was 2009 and the time before that was so long ago that I only remember bits and pieces, so I'll keep this relatively short.
Spaceship Earth: As I mentioned I don't remember much of the older versions, but I will say that I'm not a fan of the current version of the ending, the video is cheesy and clashes with the tone of the rest of the ride and there certainly must be something better they can do with the ending. Spaceship Earth is one that gets updated fairly regularly anyway, and so with the next update the ending is on the top of my list of things to change.
Circle of Life: Again, I have no point of comparison, but I think Circle of Life is heavy handed and obnoxious. I have no problem with preserving the environment or "going green," but this show just does not work for me. If they want to promote environmentalism it'd be better to do it with a more serious tone than having three beloved characters degraded to mascots for a political agenda. This one definitely needs to be replaced.
Journey Into Imagination! with Figment: This one is awful. There's nothing here that sparks imagination, just revulsion; Figment is loud and obnoxious, the ride is trite and uninteresting, and the Imagination Institute theming is now irrelevant since Honey, I Shrunk the Audience is gone. In a land that's focussed on the Future I think looking backwards is a bad idea, but this is one of the few instances where I'll say without hesitation change it back. You're not going to get any better than the original here.
Captain EO: Captain EO is a fun bit of nostalgia, but let's be honest, it's pretty clear that in both parks its nothing more than a placeholder. Honey, I Shrunk the Audience had past its expiration date, but WDI hadn't come up with something new for the space yet so they capitalized on the Michael Jackson mania. I like Michael Jackson, and I don't mind the show, but I'm ready for a new attraction to take its place.
Test Track: To me Test Track has always felt kind of half-done. It's fun for what it is, but it should be something more than that. Hopefully this new update will bring it up to its full potential, but I guess we'll have to wait and see. I personally think the direction the pavilion should take is trying to marry the ideals of Test Track and World of Motion; a more distinct focus on transportation history combined with the excitement of a modern thrill ride.
For everything I didn't mention just assume that I'm more or less content with what's there. It may not all be perfect, but I don't see any pressing need to update, replace, or change it back.
As I mentioned in the past I love this show topic and I can't wait to hear part 2.