Hedda Gabler, through the events of the play, is an exploration of the mental state of its title protagonist, a disillusioned 29 year-old woman who has decided to marry a boring academic she has no love for, Dr. Tesman. The daughter of a powerful general, she is cruel, demanding, and deeply unsatisfied with her life.
Inter-weaved into the plot is Eilert Lovborg, a rival academic to her husband who used to have a relationship with Hedda. He is a recovering alcoholic who has penned a brilliant manuscript thanks to the efforts of Mrs. Elvsted, a married mother who sees in Lovborg her sole reason for living. Meanwhile, lurking in the shadows is Judge Brack, a man with designs of his own on Hedda...
The play is likely a favorite among literary types who love to write thousands of words on the significance of every detail. And of course, there are no shortage of interpretations for every character and what "Ibsen is trying to say", no matter how far-fetched. Yet, being open to multiple interpretations is not the same as being intellectually deep.
Frankly, this is a predictable play. While a few details are surprising, the ultimate fate of Hedda and the other characters is telegraphed very early on. In fact, all the events of the story are rather straightforward.
The themes are all executed and conveyed excellently by Ibsen, but it's a lot more simple than it is profound.
Yes, it explores middle-class dissatisfaction and the headspace of its characters. However, unlike
A Doll's House, it's not as interesting. One reason is how unrealistic and ridiculous the character of Lovborg is, whose interactions with Hedda underlie the whole play.
Without spoiling it, his personality changes dramatically for very little motivation except that the play requires it. The other non-Hedda characters are fine, if caricatured. They serve their respective purpose, and don't undergo major transformations for plot convenience. And Hedda herself is a genuinely interesting, unique character.
From what I have read, Ibsen wrote the play very quickly, in a span of a month or two, starting out with a concept of Hedda's personality and nothing else. That's the strongest part of the work, but it's a shame he didn't spend more time on the plot.
Overall, this is a worthwhile, solid play. Its lofty reputation aside, it has too many holes and not enough strong points for me to call it "great", though.