The pattern A是A, 就是…
This structure can be used to express disagreement or a different point of view: "that may be true, but...".
A是A, 就是… 
is a colloquial expression. It is used in the following way: the "A是A" structure first confirms something that was being stated before: "that may be true".
"A" is usually replaced either by an adjective or a verb.
is a colloquial expression. It is used in the following way: the "A是A" structure first confirms something that was being stated before: "that may be true".
"A" is usually replaced either by an adjective or a verb.For example:
它有用是有用……
天气好是好……
天气好是好……
Then comes 就是 "but".
Then we indicate that there is something else that downplays the significance of "A". It usually has a negative connotation.
Examples
这件衣服好看是好看，就是贵一点儿
This dress may look good, but it's a little pricey
zhè jiàn yīfu hǎokàn shì hǎokàn, jiùshì guì yìdiǎnr
这房子便宜是便宜，就是离我们公司有点远
The house may be cheap, but it is a little far from our office
zhè fángzi piányi shì piányi, jiùshì lí wǒmen gōngsī yǒudiǎn yuǎn
You can also use the following conjunctions instead of 就是:
可是
不过
只是
但是
不过
只是
但是 Examples
他帅是帅，但是不聪明
He may be handsome, but he's not smart
tā shuài shì shuài, dànshì bù cōngmíng
快是快，不过危险
It may be fast, but it's dangerous
kuài shì kuài, búguò wéixiǎn
Pay attention
Note that each conjunction has its own emotional coloring. Read more about this topic here ↓