Learn Hardcore Romanian: Acest film este bun, dar altul este mai interesant. - This movie is good, but the other one is more interesting.

So in your sentence, acest is used correctly because it modifies the noun film directly (acest film). If you wanted to use acesta, you’d say Filmul acesta este bun or Acesta este bun (without film).

Why is it acest film and not acest filmul?

In Romanian, the definite article is usually attached to the end of the noun, not placed in front as a separate word. You cannot normally have both a preposed demonstrative (acest) and the definite article suffix (-ul) on the same noun.

So:

✅ acest film (this film)
✅ filmul acesta (this film)
❌ acest filmul (ungrammatical)

When you use acest before the noun, the noun stays in its basic (indefinite) form: film, not filmul. When you move the demonstrative after the noun (acesta), you then use the definite form: filmul.

Could I also say Filmul acesta este bun, dar altul este mai interesant? Is there any difference?

Yes, that sentence is correct.

Acest film este bun…
Filmul acesta este bun…

Both mean “This film is good…”, and both are standard.

Nuance:

Acest film sounds a bit more neutral or slightly more formal / written.
Filmul acesta is very common in everyday spoken Romanian.

Grammatically, the difference is just in where you place the demonstrative:

Preposed: acest film
Postposed: filmul acesta

The second clause dar altul este mai interesant stays the same.

Why is bun after este instead of before film, like “good film” in English?

Here bun is a predicative adjective: it comes after the verb a fi (to be) and describes the subject.

Structure:

Acest film (subject)
este (verb “is”)
bun (adjective as complement)

This matches English “This film is good”, not “this good film”.

If you want “this good film” as a noun phrase, then the adjective goes next to the noun:

acest film bun = this good film
un film bun = a good film

So:

Acest film este bun. = This film is good.
Acest film bun… = This good film… (used when the whole phrase is the subject or object of another verb).

What is the difference between este and e? Can I say Acest film e bun?

Este and e are forms of the same verb a fi (to be).

este – full form, neutral/standard, common in writing and careful speech
e – shorter, very common in everyday speech and informal writing

Both are correct in this sentence:

Acest film este bun, dar altul este mai interesant.
Acest film e bun, dar altul e mai interesant.

The meaning is identical; e just sounds more colloquial.

Why do we use altul instead of alt in the second part?

Alt is an adjective: it must modify a noun.

alt film = another / a different film

Altul is a pronoun formed from alt + the definite article -ul, and it means “the other (one)” / “another one” by itself, without repeating the noun:

altul = the other one (masc. sg.)

In your sentence, the second clause doesn’t repeat film, so Romanian uses the pronoun:

…dar altul este mai interesant.
= “…but the other (one) is more interesting.”

If you said alt film, you would have to say the noun too:

…dar alt film este mai interesant.
= “…but another film is more interesting.” (with a different nuance)

How does altul show gender and number? What would it be for feminine or plural nouns?

Altul agrees with the implied noun in gender and number. The main forms are:

Masculine singular: altul
- Acest film este bun, dar altul este mai interesant.
Feminine singular: alta
- Această carte este bună, dar alta este mai interesantă.
Masculine plural: alții
- Acești băieți sunt cuminți, dar alții sunt mai zgomotoși.
Feminine/neuter plural: altele
- Aceste filme sunt bune, dar altele sunt mai interesante.

Each form replaces “other + [noun]” when the noun is understood from context.

How does the comparative mai interesant work, and where do we put mai?

Romanian forms the regular comparative of adjectives with mai + adjective:

interesant = interesting
mai interesant = more interesting

Placement:

mai goes directly before the adjective:
- mai interesant, mai bun, mai mare, mai frumos, etc.
In a sentence with este, you get:
- este mai interesant = is more interesting

So in your sentence:

altul (subject)
este (verb)
mai interesant (comparative adjective)

You can add a standard of comparison with decât:

Altul este mai interesant decât acesta.
= The other one is more interesting than this one.

Why is it mai interesant and not mai mult interesant?

For adjective comparatives like “more interesting”, Romanian uses mai + adjective, not mai mult + adjective.

✅ mai interesant = more interesting
❌ mai mult interesant (unnatural / incorrect as a simple comparative)

Mult is mainly for quantity or as an adverb with verbs/nouns:

mai mult timp = more time
mănâncă mai mult = he/she eats more

If you want to intensify the comparative (“much more interesting”), you can say:

mult mai interesant = much more interesting

Note the order: mult mai interesant, not mai mult interesant in standard usage.

How would you say “This film is good, but the other one is better” in Romanian?

You can say:

Acest film este bun, dar celălalt este mai bun.

Breakdown:

Acest film = this film
este bun = is good
dar = but
celălalt = the other one (masc. sg., more clearly “the other one”)
este mai bun = is better (literally “is more good”)

You could also say:

Acest film este bun, dar altul este mai bun.

This is grammatically fine, but altul can sound more like “another one” generally, whereas celălalt usually means “the other one (of two / of a known set)”.

Can the word order be changed, for example starting with Altul?

Yes, Romanian word order is fairly flexible, especially for emphasis. For example:

Altul este mai interesant, dar acest film este bun.
= The other one is more interesting, but this film is good.

This version puts focus on altul (“the other one”) by mentioning it first.

You can also move the subject after the verb for a different nuance:

Este bun acest film, dar altul este mai interesant.

The neutral, unmarked order, especially for learners, is the one you already have:

Acest film este bun, dar altul este mai interesant.

How would this sentence change if film were feminine, like carte (“book”)?

You need to change all the words that agree in gender (demonstratives and adjectives) to feminine singular:

Masculine (original):

Acest film este bun, dar altul este mai interesant.

Feminine version:

Această carte este bună, dar alta este mai interesantă.

Changes:

acest → această (feminine demonstrative)
film → carte (feminine noun)
bun → bună (feminine adjective)
altul → alta (feminine pronoun)
interesant → interesantă (feminine adjective)

Is dar the only way to say “but” here? What about însă or other words?

Dar is the most common and neutral word for “but”:

Acest film este bun, dar altul este mai interesant.

You can also use însă, which is very similar in meaning, sometimes a bit more formal or literary:

Acest film este bun, însă altul este mai interesant.

Both are correct.

Another contrastive conjunction is ci, but it is used after a negation (“but rather”):

Nu acest film este bun, ci altul.
= It’s not this film that is good, but the other one.

In your original affirmative sentence, dar or însă are appropriate; ci would be wrong.