I actually prefer intermission-less plays, if they are realism, because I think that adhering to such a strict form forces the writer to pick a particularly heightened moment with which to begin the story: one from which 90ish minutes of uninterrupted drama can flow.
For other styles of plays, and for musicals, which (due to there being music involved, and in my opinion) never quite achieve the same level of audience submission to the reality of the work, I don't really care whether there's an intermission or not.
That being said, I don't think the length of a piece should determine the price of admission.
"We don't value the lily less for not being made of flint and built to last. Life's bounty is in it's flow, later is too late. Where is the song when it's been sung, the dance when it's been danced? It's only we humans who want to own the future too."
- Tom Stoppard, Shipwreck