I like that some bands take their older stuff and remaster it, making it sound better as if it released today. Some bands are great at doing it, but some bands destroy their work by doing it for whatever reason.
Take Megadeth for example. The Cryptic Writings album is an album that's not that popular or liked by fans of the band but I enjoy it a ton and I think its great, one of their best albums with the last great lineup. The original version of the album sounds flawless but Dave Mustard Stain went with a George Lucas approach and added stuff to some of the songs, changed them, and removed some things too in the remastered version. Nothing major, but easily noticeable when listening and it just doesn't feel right. He did this for every album pre-2000 and it's rare to find the original versions anywhere.
Iron Maiden I think are a good example for remastering their music. The only change I noticed on their older stuff was the removal of the intro from the song Powerslave which was basically the outro of the previous song Back in the Village. Other than that, their music sounds really great in the original and remastered versions respectively.