I think our movies rely on CGI and explosions more than in past movies when such technology was limited. I would cringe if someone tried to do a Bladerunner or Mad Max today.
It depends on the movies you watch... Some action films are all about the CGI (Transformers) and handle it well, giving us a fun time. Others are more grounded for their action. And the dramatic movies don't really fall into this trap... Sure, we see lots of remakes, but we also see some well-made original movies coming out.
The same can be said of video games. Games like Ultima 4, Fallout 1, Planescape, Baldur's Gate, and so on keep hitting the best ever charts.
And new games are in the rankings right there with them. KOTOR 1, Mass Effect, Halo: Reach, Red Dead Redemption, Elder Scrolls and Fallout 3... They're all considered excellent video games, standing proud among the best in the business.
Games are now dumbed down and shortened and made more expensive at the same time. Even action games have scene similar declines.
It depends on what genre of game you look at... Just about anything by BioWare (though I'm not sure about Dragon Age 2) will take upwards of 30 hours, IME. Batman: Arkham Asylum is a wonderfully-solid game and provides a fun experience and good story for a good 10 hours, as I recall (and Arkham City will have roughly 30-40 of content in it). Red Dead Redemption was a massive open world, filled with stuff to do, as are the Elder Scrolls games and Fallout 3. People have logged literally hundreds of hours into those.
There was more to do, a larger area to explore, and more vehicles to play with in Grand Theft Auto 3: San Andreas, than there was in GTA 4.
Correct me if I'm wrong (as I don't play GTA and am working from memories of reviews), but didn't GTA 4 also deliver tighter gameplay and a more-meaningful story? I'd say there's improvements in there...
Our fantasy fiction is weaker than the talent that created the genre during the pulp era.
While I don't dispute the skill and importance of the founders, dismissing every modern writer as "weaker" sounds a lot like Ebert's opinion on video games. There's a lot of good fantasy stuff getting published and it's quite enjoyable. Is it up to your standards? Apparently not, judging by your post. In which case, go ahead and stick to your favorites. Everyone deserves to enjoy themselves. But don't dismiss everything else, just because you favor a different flavor.
Our musical talents seem to just remix awesome songs from the 70s to 90s.
Again, depends on your point of exposure. There are a number of artists I quite enjoy who put together good music, all on their own. Are they big here in the States? Not so much... but you can find them nonetheless (Amazon!). And plenty of them have quite a following overseas. And there are the excellent bands from the 70s and on still persisting and even thriving in today's market. It all depends on personal taste.
(Note: Most, if not all, of my modern music is in the metal genres. Take that as you will. But I will also love my classic rock to the end of my days.)
So it's not just a decline in comics, but a decline in our civilization in general.
While I do agree with this final point, I do so based on different criteria.

I feel our storytelling shifts, changes and, as Starman said, follows something of a cycle. Society, IMO, is reaching one of the lower points of the cycle. But that doesn't necessarily mean most/all stuff from the recent era is garbage compared to older material.
ON TOPIC:
I can't really say that I've been disappointed by any comic runs, as I really don't follow much in the way of comics. I've picked up Watchmen and a couple of the Hellboy collections, but that's all. And I found both to be excellent, in their own ways and for different reasons.
In other media, I've been disappointed. I found the recent Thor movie to be a bit of a let-down, compared to the other superhero movies this year (especially Captain America). It was still good and I'm glad I saw it when I did, but I just felt it didn't measure up to the quality of the others.
And I didn't care for Red Dead Redemption when I got it for 360. Too much riding around on the horse, too bleak of a story, and not enough characters I found to be decent people. It's hard to like a game when you only like a tiny handful of minor supporting characters. The reviews I read and the people I talked to talked about how engaging it was, how well the game area was crafted, the interesting cast, etc. And I just didn't feel it. So I traded it in and got a different game I would prefer to have.
And I muddled my way through The Elric Saga: Part 1, then just dropped Part 2 as I was bored to tears and couldn't stand what I saw as cheesy brooding on the part of the "engaging" main character.