England is clearly the better League, that is a well known. Other than La Liga, it's probably the best in Europe at this moment in time. Anyone can win in one off games, as Liverpool have proven over the last few years and Spurs througout there history.
Moutinho does have to prove that he can do it week in week out in a bigger League, and I'm sure he will. He's a good player, and it's was hilarious seeing some Evertonians trying to write him off as a nothing player on one performance. 
I honestly don't see him as an improvement on a fully fit Arteta to be honest, who can do everthing Moutinho can do and more, aswell as being slightly bigger and physically able.
		
		
	 
Can Arteta play 50 matches a year always at full steam?
Can Arteta be cover for the players around him in defensive duties?
Can Arteta run up and down the pitch for 90 minutes?
Does he like to trail his opponents?
I think on the defensive department Moutinho is clearly an improvement, without losing the ability to retain possession and the ability to deliever the ball well and still arranging time to get into the box.
If you tell me Arteta has better technical attributes, I can concede that he has better dribbling ability and a probably a better long pass.
He's bigger? Yes, slightly. But Moutinho is more aggressive, marks his defensive area better and has a higher work rate.
Can Fellaini play the ball around like Moutinho? Does he win as many balls as Moutinho? Does he run as much as Moutinho? Can he position himself as well as Moutinho? I'd say no to all.
Moutinho's intelligence allows him to play against any opponent. There aren't many players in the game that can read and understand the movement and marking. He's no Messi, allright. He never was and he'll never be.
But we're not talking about Messi as standard for an Everton squad player, are we?
The English League is the most exciting, I admit.
Is it the best in the World? Doubt it, mate.
Right now, La Liga has a higher number of very good sides. The top 3 players in the wolrd play in La Liga.
Pull the top 4 out of the EPL and you have a pretty ordinary competition. Still better than portuguese league, I don't question it, but most of the teams wouldn't have a walk in the park against a top table portuguese side. And clearly they wouldn't be a match for any of the top spanish sides.