Why just read the book? Download Squeak - a bit far from the mainstream expectations, but it's free in the best sense. Or you can get VisualWorks Non-Commercial. (There's a very under-appreciated ASP-like web app framework in VisualWorks!)
Having a book handy means I have something to turn to the next time I give it a go.
Smalltalk is radically different in a fundamental way when it comes to your relationship to source code and the dev environment. All your source code changes are in something like a transaction log. When you're programming, you're just manipulating the meta-level more or less directly. When you do get it, there's a "whoa!" experience. Better yet, persevere and "get it" then go back to something like iPython. You'll get a real perspective shift!
But being born and raised on the commandline, it's Smalltalk-the-Environment which causes me trouble. I often find myself wishing that I could just play with it like you would with, say, Ruby's irb. I find the conventions (having to highlight code and hit Ctrl-I to get it to run, and so on) quite off-putting. If I can get over that, I'm sure it'll be worth it, but it's a bit of a struggle.
If you want something like a command line, you can write it fairly easily. You could probably subclass it from the Workspace.
But why would you want to? Most Smalltalks have lots of context-aware goodness! If you are browsing on the class side, highlighting code and executing does it in the context of the class. If you are looking at an instance in the inspector, it does it in the context of that object instance! If you are in the debugger, writing and executing code does it in the context of that stack frame!
Those last two bits of context-awareness have been the environment where I have done some of my best debugging and coding in the past decade!
Command-line or highlight/right-click is only the medium. The message is the thing! Think of it as like adjusting to the controls of a new video game.