This is a personal opinion, however, it could still be valuable information for anyone deciding on a bracket.
20-24: I have decided to take this character and my other 24 twink to a higher bracket, and likely the 49 bracket, for the following reasons:
1) Too low of health. Things, including myself, die too quickly.
2) Heals are very powerful at this level, specifically Priests with their bubble.
3) I need more spells.
4) I need more than two choices for BGs.
THIS IS NOT A COMPLAINT - I am simply just expressing my opinion of this bracket and I have decided to move on up :) Hope people looking for a bracket were able to take some of this information into consideration.
Even though it's just the 20-24 bracket, you still need to put considerable effort into finishing your character.
Check out my 24 lock's armory
1. It's super important to be hit capped (6%) so your fears and burst damage does not miss.
2. Demonology is not very good until much later in the game (it's more of a gimmick spec). You would be much better off as Destruction or Affliction (I prefer Destro atm).
Also, I wouldn't move up to the 29 or 39 brackets atm, they do not have activity. 29s do not have the numbers or interest for a revival right now, as many people are MIA for the holidays or in general. The 39s are planning on trying for games this Wednesday, but it's a lot of work to finish a 39 before then, especially if games don't end up happening.
24s are the only bracket right now which has consistent activity (24-7 pops) and a lot of people are migrating to that bracket from other places. 49s are a good bracket (a lot of fun) but 24s are equally fun depending on who you end up playing with. Many of the level 20 F2P twinks are skilled players and games consisting of 20s/24s group queuing are usually quite fun (and competitive).
I would give the 24 bracket a second chance, since it's going to become the new go-to bracket for twinking, much like 19s were in the past.