French so different from other romance languages

[Mens-Sarda]

it's strange how all northern Italian languages have these strange sounds like ö ü etc.etc. Germanic or Celtic influence? or both?

Sardinian language has nothing like that, the vowels are really simple, at least the northern Sardinian, while the southern Sardinian has several ways to pronounce vowels, more or less like Portuguese

[Ouistreham]

it's strange how all northern Italian languages have these strange sounds like ö ü etc.

Not all of them. Only Piedmontese, Lombard, Ligurian, and the dialects of Emilia-Romania.
Venetian, Ladin, Friulan and other Rhaeto-Romance languages never used those vowels.

This geographical distribution (like a triangle, or a wedge extending towards South-East) delivers the answer to the second question:

Germanic or Celtic influence? or both?

Influence from France, obviously, as a result of Charlemagne's invasion of the year 774.
This influence was most powerful in Piedmont (early Piedmontese became virtually a variant of Provençal, cf. the Sermoni Subalpini) but lost momentum as long as it proceeded along the Via Emilia. Tuscany and Veneto remained untouched.

[Comte Arnau]

The pronunciation of French is definitely what makes it look more 'different' or I'd rather say 'eroded'. But in terms of core vocabulary, I have my doubts. The Portuguese-Spanish block forms often an island that leaves them apart from the French-Occitan-Catalan-Italian block.

And I don't mention Romanian because it's a world apart.

[Leo Iscariot]

French and Italian are both Occitano-Romance languages

Actually, neither are Occitano-Romance. French is Gallo-Romance, and Italian is Italo-Romance.

Occitan and Catalan (And all their dialects) are the only ones that are Occitano-Romance.

[Sikeliot]

Don't let the massive difference in pronunciation fool you. French is closer to Italian than Spanish is. The only reason it's less mutually intelligible is because of the pronunciation.
French and Italian are both Occitano-Romance languages whereas Spanish comes from a different group, much older, it's under the Iberian Romance along with Portuguese, so it has more in common with Portuguese than it does with Italian.I'm not saying that Italian and Spanish are nothing alike, all I'm saying is that French is in fact closer to Italian and the only reason why they are not as mutually intelligible is because of their huge pronunciation differences.

In terms of vocabulary, yes this is true.

[Guapo]

Eastern block

Love that phrase

[Arbërori]

To be honest, French isn't all that different from other Romance words when you can speak it fluently.

I love speaking French and I love doing it French...

[Arthur Scharrenhans]

Not all of them. Only Piedmontese, Lombard, Ligurian, and the dialects of Emilia-Romania.

Not even all the dialects of Emilia-Romagna; in fact, nowadays just Western Emilian (West of Parma), plus some remnants in more archaizing zones along the river Po and in the highest valleys of the Apennines. Historically, front rounded vowels have been retreating along the Via Aemilia - the dialect of Parma used to have them not so long ago, and they probably stopped at the Panaro river (between Bologna and Modena) in older times.

[Arthur Scharrenhans]

The pronunciation of French is definitely what makes it look more 'different' or I'd rather say 'eroded'. But in terms of core vocabulary, I have my doubts. The Portuguese-Spanish block forms often an island that leaves them apart from the French-Occitan-Catalan-Italian block.

And I don't mention Romanian because it's a world apart.

Many years ago I read somewhere that, grammatically and lexically, Italian and Spanish are both closer to French than they are to one another; it's the more conservative pronunciation of both (Castilian) Spanish and (Tuscan) Italian that makes them look superficially similar.

(And we all know that in linguistics shared retention of archaisms doesn't prove an especially close relationship.)

So you're basically right about French and Italian sharing several traits setting them apart from the Iberian block; OTOH, French and Spanish share some 'Western Romance' traits setting them apart from (Central-Southern) Italian.

[TheForeigner]

But how strong is the Germanic influence on French language, especially pronunciation and spelling and grammar and vocabulary too. What about Celtic influence? Why does it sound so strangeor distinct compared to other Romance languages?