"Kia plezuro!"

Translation: What a pleasure!

[Betigre]

Tio estas tio, kion ŝi diris!

[mizinamo]

"estas tio" - no accusative after "estas". (But "kion" after the comma, as you wrote, since that one is the object of "diris".)

[Betigre]

dankon, mi jam korektis ĝin

[Thomas_Slo]

Would somebody clarify the question word "kia" for me? In the tipps we got the example "Kia vi sentas vin?" but personally I would use "Kiel vi sentas vin?" as in "Kiel vi fartas?".
Are they synonyms?

[mizinamo]

kiel asks for an adverb, kia for an adjective.

You would say Mi fartas bone (I am "faring" well) with adverb bone "well"; but Mi sentas min laca (I feel tired) with adjective laca "tired".

[Thomas_Slo]

So...
Kia estas la domo? Gxi estas bona / granda / bela / ...?
vs.
Kiel vi kantas? Mi kantas bone / bele / afable / gxuste / ...?

[mizinamo]

Precisely!

[aidanmokal]

Sed, cxu oni ne dirus "mi sentas Sin Lace", cxar la subjekton de la frazon "laco" apliki al?

[mizinamo]

No -- it's min, not sin, because sin only refers back to a third-person subject (li, ŝi, ĝi, ili), and to the best of my knowledge it's laca, not lace, for the same reason that it's "I feel happy" and not "I feel happily".