1. Culling of stratholme (really, nothing good about this instance, at least it's okayish when you can skip the rp).
2. Violet Hold. Instance gets completely ruined by the inability to chainpull, means that it takes ages to complete and you are unable to get anything resembling a challenge.
3. ToC. Just boring, but at least it's quick.
4. Oculus. The dragon part is remotely fun, once.
5. Blackrock depths. I feel like I'm being a bit unfair, the instance would be fine as a raid/with guildies, but seriously, such a big instance with random groups is just asking for trouble.