How to compare languages and their difficulty

There are two major stages in studying languages:

1) Learning how to correlate the written language to pronounciation

2) Learning the grammar and vocabulary

For the languages I had experience with learning or simply read or heard about, below are my ratings. I tried to remove my Euro-centric bias as much as possible.

Language	Reading	Grammar
Chinese	Extremely Difficult	Easy
Danish	Difficult	Easy
English	Difficult	Easy
Esperanto	Easy	Easy
Finnish	Easy	Extremely Difficult
French	Difficult	Medium
German	Easy	Difficult
Greek	Easy	Medium
Hebrew	Difficult	Medium
Japanese	Difficult	???
Korean	Easy	Medium (???)
Russian	Easy	Difficult
Spanish	Easy	Medium
Tatar / Turkish	Easy	Medium / ???

Disclaimer (2004): OK perhaps there's really no such thing as an absolute difficulty of a language, even if you break it up this way. What makes a language easy or difficult is the perspective from which you are coming. That applies both to pronounciation and grammar.

Still, I don't want to give up completely on the notion of language difficulty. It's not really fair to say that everything is completely relative.

In reading/pronounciation we can talk about how consistent reading rules are. Consider for example alphabetical writing systems. Is there a letter for each phoneme in the language? If not, is there a combination of letters to represent each sound? Are those combinations consistently pronounced? If there are silent letters, are they consistently silent? Are letter combinations read in predictable ways or are reading rules infested with exceptions? These are the criteria by which I rated Danish as a difficult language to 'read', while Russian and Spanish as easy.

As far as grammar is concerned, we can compare such grammatical constructs as verb inflections / noun cases, adjective conjugations, concepts of tense, etc.. The more of those, the more complex. Or if a language X has a grammatical concept unknown in language Y, a speaker of language Y will have a hard time grasping X.

For example, a Russian speaker might have a hard time with definite / indefinite articles in English, while an English speaker might have difficulties with noun inflections. A Chinese speaker will have a tendency to have trouble with past and future tense, and a Finnish speaker will have trouble conjugating words by gender and making the distinction in the gender pronouns he/she/it.

Generally, a speaker of a difficult language should find an easy language easier (isn't' that amazing?), because he/she just has to simplify his grammatical constructs, instead of learning new ones. I suppose it would be more appropriate to say a language is difficult in this or that respect rather than as a whole.

Then there's other issues in learning a language, such as how formational a language's vocabulary is. For example, are words related in meaning similar to each other, differing only by prefixes, etc. or are they completely different (borrowed from different languages perhaps). There's the question of how easy it is to guess a word's meaning if you know its constituent parts.

Obviously, I'm not a linguist, and there's plenty of literature on this regard that explores these issues better and use more standard terminology. But these are my thoughts based on some exposure to several languages.