Unlike Proton and Toyota they don't do CKD with the mentality of, "hey! lets CKD this car in malaysia, we'll make it cheap!! my pakcik got glass factory, my brother-in-law got bumper factort, etc.....quality nevermind lah....gov protect us....rakyat no choice but to buy our cars....why so care? we make money first lah! my lembu want to stay in bangsar condo!!" 

VW Polo Sedan 2014 spec is not really a facelift but CKD version, has some slight upgrades and additions. One thing which really surprised me is the addition of rear aircon vents, most C-segment cars don't have this yet this B-segment car has it.

In terms of spec you can't go much wrong with this car, decent 1600cc engine (similar type of technology to iVTEC), 6 speed gearbox with paddle shift (wet box not DSG, higher reliability replaces higher gear change speed), traction control (about the only other b-segment car with this is the Ford Fiesta and Honda City, not too sure about Pug 208), 5 stars safety rating, etc.

NVH? I'd say better than its peers, even a much more expensive Honda Civic suffers from wind noise.
Underpower? Depends on your driving style. Fuel consumption is tied to this.
Maintenance? Not too sure about this model usual for TSI engined model is 600-800 for minor, 1000-1600 for major.
Depends on who you hear from it can vary from wonderful to tragic.
The typical uneducated or dunno anything about cars will say it is horrible, "my friend ah! buy this car hor! everyday go workshop fix wan! then ahh...ford resale so telibel!! wan to sell oso cannot price no gud!!" 

I've heard it a thousand over times from people like that, they're also the same folk that don't follow the owners manual when it comes to servicing, don't service at the service center, use the cheapest possible parts and consumables when go service. Those people should just stick to buying old tech Proton Saga's then go ABC workshop for the RM38 service promo when they feel like it once a year.

When it comes to good cars you need to make sure service is done according to the manual and follow the recommended parts from the service center or 3s. DCT require special gearbox oil, go ABC workshop put inside cap ayam gear oil sure lah die.

Fiesta like most conti's require servicing once every 10k, minor service prepare about rm500, major prepare at least rm1000. Depending on your driving usage 10k can be a few months or a year, but I don't recommend waiting a full year before going to service, most to most stretch it to 6 months before checking in.
2009 Hyundai Elantra - imho if I were to take a the plunge to buy and drive a Korean I'd rather go for a higher up model.

2006 Nissan Sentra - with this kinda budget there isn't alot of choose from so you need to search the websites and magazines for a good buy, usually anything from Nissan would be a good buy. Fundamentally, a Sentra is a good, low fc, cheap to maintain and reliable car. That is if you buy one in good condition, well 2006 is quite a long while ago, do check out the car and see if the condition is what you expected if you think it disappoints you in anyway then walk away.