While Tiguan's interior feels definitely cheaper to me compared to my '16 GTI - yes, it's missing a couple of nice touches present in my GTI which make a difference for me (although some of them are gone even from the newer GTIs as mentioned by Oliver), I think overall it's up to par with the rest of the class, except for CX-5 which IMO is more premium then anything else in the class.
No vehicle in this class, except for the newly launched '19 CX-5 Signature trim, has real wood trim or high quality leather, so one should set the expectations accordingly. None of them have velvet lined glove boxes or felt lined door pockets either so it's not something that Tiguan must have. As for the rest of the cabin, they follow the same mold as anyone else - soft touch upper dash/hard plastic lower and floor console, soft touch top for front door panels/hard plastic rear, all cubbies are lined with rubber mats, door switches are lit, etc.... Honestly, I don't see why anyone would say the Tiguan interior feels cheaper than the rest of the class. It's not like the materials are a lower grade by any means.
The biggest offender for me in the Tiguan's interior are the rear door inserts which are downright ugly and extremely cheap feeling being made of hard plastic rather than fabric/leatherette. This is one thing I strongly fault VW for. I'm not sure if they changed them for 2019 but if they didn't, I would say it's a step too much for VW and it's sad to see. The other thing for me is the short, fixed front arm rest. I would miss the sliding and height adjustable arm rest in my GTI, but again, I don't think any Tiguan competitor has something like this anyway.
I think some people still expect VW to be a notch up above the other mainstream competitors but the reality is they compete in a very aggressive segment/market and something has to give hence the Tiguan is tailored for North American market specifically and in the same price-range as everything else. You cannot realistically expect Audi materials for Honda price.
Tiguan's price and packaging is pretty good IMO too. The mid-trim Comfortline is pretty well equipped (3 interior color choices too) for just under $35K (before freight) - the only feature missing for me is HID/LED headlights and rear-heated seats (not available in any trim). I really like you can get the built-in Navi or the panoramic sunroof as stand-alone options rather than standard or package. I may choose built-in Navi/Satellite radio for a very reasonable $555 but don't want any sort of sunroof ($1400), so it would work well for me.
As for power, it's underpowerd for my liking but not for what the car is meant to be. In this segment the fuel economy trumps power every time for most buyers (not for me though) so it's a non-issue with VW approach which is no different than any other mainstream manufacturer.
The cargo/rear passenger setup is very good (perhaps the best in class IMO) with sliding/reclining rear bench, 40-20-40 split, relatively non-intrusive cargo side walls (5-seat version), plus it's spacious enough rear seats up/down (5-seat version). The cargo volume is not the absolute biggest by the numbers but its configuration is probably one of the best.