BigOnAnime

Does everything truly look good on Blu-ray?

So as Blu-ray grows in popularity, so does the number of people who eat up the "Blu-ray is always better." mentality, and those who will want to purchase those worrying their DVD's will become like VHS tapes. Truth be told I had that mindset as well. However, I later got a grasp of reality.

Blu-ray can make some shows look absolutely visually stunning, especially when it comes to remastering older shows, mainly stuff older than 2000. Take a look at some of these remasters (Please note, some shots may have spoilers, view at your own risk.).
Rurouni Kenshin: Trust & Betrayal
Rurouni Kenshin: Reflection
Howl's Moving Castle-This is the biggest improvement over the DVD I have ever seen.
Serial Experiments Lain
The Vision of Escaflowne

Now for stuff that was released when Blu-ray was around, as in the stuff was released on both Blu-ray and DVD. Things can look pretty freaking awesome still.
Neon Genesis Evangelion 1.11: You Are (Not) Alone
Neon Genesis Evangelion 2.22: You Can (Not) Advance
Redline
Nichijou: My Ordinary Life
Hanasaku Iroha
Mobile Suit Gundam Unicorn

So, where is your "Blu-ray isn't always better claim" supposed to be? Well, here it is. Believe it or not, Blu-ray doesn't always have a massive advantage over the DVD. Sometimes it can look only a little better than the DVD (An upscale), or it can look worse than the DVD (A poorly done upscale). Prepare to see the horrors of shitty Blu-rays. If you thought Blu-ray was always better (And on a massive scale), prepare to be shocked.
Shakugan no Shana
Shakugan no Shana Second
Fairy Tail-Note, no Blu-rays for the show exist in Japan. FUNimation did their own (poor) upscale.
FLCL
Gankutsuou: The Count of Monte Cristo-Notice clearly in the 4th shot how the DVD has more lines in her hair than the Blu-ray does.
Blue Submarine No. 6

What's wrong with these shots? The problem is the smudging and smearing of lines, resulting in blobs of colors. If you've watched a ton of anime, you'd know none are supposed to look like that.

Now, upscales that don't look like shit. Many of these are worth the money, others, not so much as you could get the same result from upscaling the DVD.
Ga-Rei-Zero
Last Exile
Baccano!
Chobits-To my knowledge, no Blu-rays for Chobits exist in Japan, so this would be just another FUNimation upscale.
Spice & Wolf Season 1 (US BD)-Look at the post below it for comparisons between the Japanese BD, and FUNimation's BD.
Paranoia Agent

So all in all, it really depends on the title. Many Blu-rays can look fantastic (When remastered properly), others can be good/decent upscales, andsome look like they came out of a garbage can, mainly just so the studio could make a quick buck. Most Blu-rays for newer shows look quite good (I have seen/heard of a few examples where it doesn't look good or stellar such as Panty & Stocking with Garterbelt and Chu-Bra!! however), so those are on the safe side. As Blu-ray becomes more dominant for anime in Japan (Most Blu-rays in Japan are for anime), and anime DVD's die out, prepare to get used to Blu-ray more.

Where I got these shots:
http://muhootsaver.tistory.com/notice/1294

Some things to note, that blog is no longer updated by the creator anymore (He does use his Twitter account still, and has updates there), but it still has an abundance of screenshots, and will remain quite useful. Also, any links leading to a place called "The Fandom Post", some things happened to that place, so any links that don't work (As a result of what happened there), change "/forums" to "/oldforums", and the URL will then work.