I think I have heard this kind of sentence before, and searching on google I found a couple instances. When you repeat an adjective (and perhaps verbs as well) to show that you've done / feel a certain way but not to the point that the listener might expecting. Or maybe to soften your negative opinion.
美味しいは美味しいけど。。。 It is good but... / it is not that it isn't good but...(reminds me of 美味しくなくはないけど)
好きは好きだけど。。。I do like it but... / it is not that I don't like it but...
couple instances I found online:
So my questions are:
1 - How grammatical is this? Is it more like something you'd only use conversationally?
2 - Can it only be used with adjectives, or maybe with verbs as well? (eg. 観るは観るけど、興味があんまりない。)