Ruby delivers on the promise of being "optimized for programmer happiness." But I think that in order to experience that you have to become fairly immersed. In fact, some of the best parts seem outright offensive at first (question marks in method names?!). No language is perfect. But once you get past the idiosyncrasies, I honestly do think Ruby feels better. That's pretty esoteric, so I'll try to call out some specifics as well.

I agree with most of what's already been said, but I'll try to add a few things. In order of most to least significance (for me):

The standard library, especially with regard to collection methods. Want to slice/filter/sort/chunk an array/hash in some weird way? Ruby's standard library almost certainly supports it. So many amazing things are built-in across the board.

Not relying on indentation for scoping. It's one of my biggest beefs with Python. Yes, of course, code should be indented properly. But goodness....let my linter enforce that, not the interpreter. I don't love ruby's do/end keywords (I prefer curly-braces), but at least having a visual cue for end-block is a vast improvement over python.

A more consistent interface. Everything is an object, and you invoke methods on those objects. I think [].size just makes more intuitive sense than len([]).

Great readability boosts from things like question-marks or exclamation-points in method names (admittedly that felt gross and wrong at first), trailing if-statements, unless-conditionals, invoking methods without parens (though I only sanction this if not passing args).

A more helpful, less snobby community. 100% just my personal experience, maybe I've just had bad luck with pythonistas.

No __init__.py nonsense. Maybe that's fixed/improved in python3? But I hate it. In fact, I hate any use of dunders...littering the code with unreadable symbols.

Python Example

Functions are first-class variables in Python. You can declare a function, pass it around as an object, and overwrite it:

def func(): print "hello"
def another_func(f): f()
another_func(func)

def func2(): print "goodbye"
func = func2

This is a fundamental feature of modern scripting languages. JavaScript and Lua do this, too. Ruby doesn't treat functions this way; naming a function calls it.

Of course, there are ways to do these things in Ruby, but they're not first-class operations. For example, you can wrap a function with Proc.new to treat it as a variable--but then it's no longer a function; it's an object with a "call" method.

Ruby's functions aren't first-class objects

Ruby functions aren't first-class objects. Functions must be wrapped in an object to pass them around; the resulting object can't be treated like a function. Functions can't be assigned in a first-class manner; instead, a function in its container object must be called to modify them.

def func; p "Hello" end
def another_func(f); method(f)[] end
another_func(:func)      # => "Hello"

def func2; print "Goodbye!"
self.class.send(:define_method, :func, method(:func2))
func                     # => "Goodbye!"

method(:func).owner      # => Object
func                     # => "Goodbye!"
self.func                # => "Goodbye!"    

I, like you, looked for inject and other functional methods when learning Python. I was disappointed to find that they weren't all there, or that Python favored an imperative approach. That said, most of the constructs are there if you look. In some cases, a library will make things nicer.

A couple of highlights for me:

• The functional programming patterns you know from Ruby are available in Python. They just look a little different. For example, there's a map function:

    def f(x):
        return x + 1
  
    map(f, [1, 2, 3]) # => [2, 3, 4]
  

  Similarly, there is a reduce function to fold over lists, etc.

  That said, Python lacks blocks and doesn't have a streamlined syntax for chaining or composing functions. (For a nice way of doing this without blocks, check out Haskell's rich syntax.)

• For one reason or another, the Python community seems to prefer imperative iteration for things that would, in Ruby, be done without mutation. For example, folds (i.e., inject), are often done with an imperative for loop instead of reduce:

    running_total = 0
    for n in [1, 2, 3]:
        running_total = running_total + n
  

  This isn't just a convention, it's also reinforced by the Python maintainers. For example, the Python 3 release notes explicitly favor for loops over reduce:

  Use functools.reduce() if you really need it; however, 99 percent of the time an explicit for loop is more readable.

• List comprehensions are a terse way to express complex functional operations (similar to Haskell's list monad). These aren't available in Ruby and may help in some scenarios. For example, a brute-force one-liner to find all the palindromes in a string (assuming you have a function p() that returns true for palindromes) looks like this:

    s = 'string-with-palindromes-like-abbalabba'
    l = len(s)
    [s[x:y] for x in range(l) for y in range(x,l+1) if p(s[x:y])]
  

• Methods in Python can be treated as context-free functions in many cases, which is something you'll have to get used to from Ruby but can be quite powerful.

In case this helps, I wrote up more thoughts here in 2011: The 'ugliness' of Python. They may need updating in light of today's focus on ML.