I migrated from Bash to Zsh in October and I'm quite thrilled with zsh.

Motivation

What motivated me to finally move?

1. I no longer used the shell within Emacs. If you have a bash setup that works well in Emacs, don't try to switch. Since moving from emacs bindings to evil-mode, I am quite comfortable in Vim, so I find myself using iTerm way more than the Emacs shell.
2. While doing some pair programming with @jakeonrails, I saw the coolness of zsh, which he pointed out to me "was no big deal", just what's on the Railscasts Episode on Oh My ZSH.

Tips on Migrating

Here's a few tips to somebody migrating might find useful:

1. Try out oh-my-zsh and take a look at the themes examples. The themes seem to be all customizations of the prompt. I'll share what I came up with at the bottom, which is a modification of the default robbyrussell theme.
2. While most of your bash code will migrate as-is, this is a good time to clean up some cruft in your files. I like to organize my shell code into small files, each with a particular theme, and then have the .zshrc source those, rather than having a giant .zshrc file.
3. The oh-my-zsh plugins are way for you to share shell configuration with other members of the community. It's simple to read what those plugins are doing. Many are just setting aliases. I started to migrate my own configuration code by converting to plugins, but then I realized that that's overkill. If I ever want to share the configuration, at that point, I can convert to a plugin, which is quite simple.
4. If you have any shell functions that use [, you might have escape that character for zsh.
5. If you install zsh plugins, be very careful with any newly installed aliases from the plugins. I previously had gl aliased as 'git log' and the git plugin uses gl for git pull, which caused me a huge headache when I ran that within my octopress branch.
6. You need to escape the ^ character for commands such as git reset HEAD\^

Migration Notes

Escape []

In the third line of this function, I had to escape the [ and the ].

opost() {
  cd $OCTO_HOME
  output=$(rake new_post\["${1}"\])
  new_file=$(echo $output | awk '{print $4}')
  base=$(basename $new_file)
  new_location=$OCTO_HOME/source/org_posts/
  mv $OCTO_HOME/$new_file $new_location
  echo created $new_location$base
  cd -
}

My new zsh prompt

To set this up, I created a custom theme called justin808 by doing the following:

1. Create a theme file oh_my_zsh/custom/justin808.zsh-theme. See below.
2. Export the theme name.

This is what it looks like in my .zshrc file. The first line is because I moved my ZSH configuration files.

export ZSH=$HOME/.oh-my-zsh
export ZSH_THEME="justin808"

Here is my theme file oh_my_zsh/custom/justin808.zsh-theme

hostname=`hostname`
if [ $hostname != "$HOME_HOST" ] || [ $USER != "justin" ]; then
  host_stuff='%n@%m:'
else
  host_stuff=''
fi
PROMPT='%{$fg_bold[red]%}➜ %{$fg_bold[green]%}%p ${host_stuff}%{$fg[cyan]%}${PWD/#$HOME/~} %{$fg_bold[blue]%}$(git_prompt_info)%{$fg_bold[blue]%} % %{$reset_color%}'

# display exitcode on the right when >0
return_code="%(?..%{$fg[red]%}%? ↵%{$reset_color%})"

RPROMPT='${return_code}$(git_prompt_status)%{$reset_color%} [%*]'

# RPROMPT='[%*]'
ZSH_THEME_GIT_PROMPT_PREFIX="(%{$fg[red]%}"
ZSH_THEME_GIT_PROMPT_SUFFIX="%{$reset_color%}"
ZSH_THEME_GIT_PROMPT_DIRTY="%{$fg[blue]%}) %{$fg[yellow]%}✗%{$reset_color%}"
ZSH_THEME_GIT_PROMPT_CLEAN="%{$fg[blue]%})"
GIT_PS1_SHOWUPSTREAM=verbose

ZSH_THEME_GIT_PROMPT_ADDED="%{$fg[green]%} ✚"
ZSH_THEME_GIT_PROMPT_MODIFIED="%{$fg[blue]%} ✹"
ZSH_THEME_GIT_PROMPT_DELETED="%{$fg[red]%} ✖"
ZSH_THEME_GIT_PROMPT_RENAMED="%{$fg[magenta]%} ➜"
ZSH_THEME_GIT_PROMPT_UNMERGED="%{$fg[yellow]%} ═"
ZSH_THEME_GIT_PROMPT_UNTRACKED="%{$fg[cyan]%} ✭"