Centurion

Not really. The 135i is a miniature GT which the TT is a strict 2 seater performance orientated car. Despite the superb engine the 135i doesn't offer the same experience as the true sports car TT, Z4 and Boxster. The 135i is still a capable car though, might even be a bit more exhilarating to drive than the 4 wheel drive TT.

Guibo

Price is indeed a big factor. They even write: "The Golf GTI emerges ahead of the BMW chiefly because of its price advantage."
I agree, if they'd push harder, they might have found where the 135i really shines. There weren't really any comments about understeer/oversteer, so perhaps they were driving like 90% of drivers. But really, the BMW should be just as entertaining, if not more so, even at normal use. If not, then BMW need to look at the criticisms seriously.

Regarding the interior, claims about cheap plastics and being an unpleasant place should be examined against other reviews.
AutoExpress, in its first drive review of the 135i:
"Build and material quality is top class throughout, while the car comes generously equipped as standard."
Their review of the 118d years ago:
"Inside, things get close to looking conventional, with a dash layout that resembles a scaled-down version of that in the 5-Series. This is no bad thing, though, as it means sensibly located dials and an excellent driving position, as well as a quality feel."

Autocar, 123d:
"The interior is impressive enough, with plenty of space and great-quality materials."

TopGear overview on 1-Series, Build Quality (5 stars out of 5):
"The 1-Series boasts a strong interior. Tap it and you'll hear a deep thud as if all the materials are inches and not millimetres thick. Basically, the One has the same strength as all other BMWs, including the 7-Series."

Canadiandriver.com, 135i:
"No complaints, however, about the quality of the interior fittings or the materials used. They're as nice as any other BMW, with soft-touch plastics on the dashboard, soft leather on the seats and metallic or wood-grain trim."

Channel4:
"Today's BMWs all feel solid and well put-together. Neither of the two 1-Series Coupes we've driven on a wide range of road surfaces rattled or squeaked, and everything is well finished inside and out.
You sit low, with your legs forward, and you very soon start to feel a psychic bond with the steering."