2000s were awful in my view.
Slow technological progress compared to the fast-paced changes during the 1990s.
I was constantly frustrated by subpar technologies that took one leap upwards and five steps back.
CD-Rs that could not be rewritten,
LCD screens that you could not view from the side and had these washed-out colors,
and people actually complained when those colors improved in the 2010s with LED
because "we don't like those candy colors"
Slow internet that kept being slow as webpages got larger faster.
The whole decade should have been condensed to a year.

The only good thing about it was that computer parts were cheap.
And anime.

The 2010s picked up the pace and the 2020s are just crazy,
maybe even faster paced than the 1990s.

[edit]

I see people disagreeing, so I'll double down on why the 2000s were awful.

The 2000s had Ugly 3D replacing beautiful 2D.
The 2000s had ppl tlkng l1k3 d1s.
The 2000s had Fred being #1 on youtube.

During the 2000s gross-out movies were popular.
The 2000s had the movie Idiocracy which was not a prediction, but a reflection of its time.
Because it was a painfully stupid time.
Same goes for Wall-E, who envisioned a far-future where everyone is painfully fat,
because they couldn't imagine anti-obesity drugs being invented,
despite the precursor of semaglutide having already been invented at that time.

It's also a time where 'gamer' stopped meaning having fun playing various types of games
at the arcades or Commodore 64, and instead started to exclusively mean
having the fastest rig possible in order to play a foot soldier in war games,
especially FPS shooters like Counterstrike, Quake, Unreal Tournament, Call of Duty, etc..
and to a lesser extend strategy war games like starcraft and MMORPGs like WoW.

[edit #2]

Perhaps advancement wasn't necessarily slow, but every advancement was a trade-off in the 2000s.

Beautiful 2D -> Ugly 3D
Bulky CRTs -> Bad-angle badly colored flatscreens
Curated TV -> Poor-quality internet videos
low-storage sturdy floppy disks -> Read-only fragile CDs
A whole new world of communication -> A whole decade wh3r3 ppl tlkd l1k3 d1s

The only exception, again, was anime.