Joni Mitchell finally made it to the Capitol Theater Monday night, and there's no question she proved worth the wait.

She also showed a surprisingly beguiling stage personality, capable of projecting both sensual and cerebral depth.

The fragile scarecrow image of her that comes through on TV in no way prepares one for the mature, sexy realities of Miss Mitchell in the flesh. In the same way, her recordings suffer badly the absence of the kind of dramatic nuance she can communicate in person.

Filling the void somewhere between Ingrid Bergman and Sandy Dennis, Miss Mitchell moved gracefully through a balanced program of 18 songs, all but one written by her.

Her best-known compositions were in many ways the least effective on this occasion, though a large part of the capacity house obviously came to hear the likes of Both Sides Now, Night in The City, Michael, and Circle Game. They were not dissapointed, but the familiarity of such material seems to work against it.

For instance, there's no way a hit song like Both Sides Now can ever be the fresh experience it once was before every third-rate folksinger on the continent got hold of it.

However, to Joni's credit, she did her level best to breath new life into these songs, never settling for a token run-through. Of these favorites, only Circle Game, with it's dime store buddhism, dragged on to boredom.

The less familiar material left little room for boredom, with many songs achieving a marriage of lyric and line that was breathtaking. One Man Band was such a song - so perfect, the words and melody became permanently inseparable.

Her gifts as lyricist have been widely touted, and with good reason. The images often startling, as are the seemingly illogical associations. The beauty of such images and associations is their inevitability, once sung. Though Joyce-like word-plays shunt suddenly into focus here and there, more often than not Miss Mitchell's poetic intents are visual.

This penchant for visual imagery heads her occasionally into dangerous waters that seem deep but are only muddy. The lyrics of Marcie, for example degenerated into a series of nouns which went poetically limp for want of verbal tension. At its best, though, as in I Had a King, Miss Mitchell's poetry is poignant in the extreme.

Two Houses was the best example of her piano playing. Aside from an understandable leaning towards basic triads, there was little doubt that with the addition of piano Miss Mitchell has further extended the emotional and tonal scope of her compositions.

As for the compositions, there was a sophomoric sameness to many of them. Her writing is defined by her limitations as a musician. Harmonically, she composes with monotonous reliance on simple major-to-minor- to-major progressions, and she could also use a few lessons in form as a cure for the unresolved wanderings of songs like Busy Being Free.

The protest song, Fiddle and Drum, an obvious attempt at modern classical music, was sung unaccompanied, which only served to point up the linear shortcomings of Miss Mitchell's writing. Like many of her songs it just wavered around, going nowhere in particular.

Many others, like Chelsea Morning, were very effective. Maybe it was her voice, or her beautiful lyrics, or perhaps her completely feminine stage presence.

One way or another, Joni Mitchell comes across with real honesty, and makes her mark.