I don't know what reviews you're reading or what you're expecting from the lens. I have the X-T1 and 18-135 and I think its a really good all around lens that surprised me with what it delivers. Is it as tack sharp as their best primes? Hell, no. I never expected that. Rent or borrow one and try it.
Thing is I would like for it to be a little faster and I'm not entirely sure the weather sealing justifies the drop in quality (see above).
Can you take great pictures with it? I'm sure you can, but I can also chose a lighter version. It does focus quite close though so you might get away without a macro.