The public's perception will be in the quality of the materials used for the finish of the stations as well as the trains. The bulk of the spent money will be the build and a tiny percentage will be the finish.
The cost of the Luton DART is around £200 million; including construction of the stations, and associated infrastructure, and an additional £25 million has been allocated for a new Network Rail overbridge at Luton Airport Parkway railway station.
Looks like the cost is already up another £25 million before work even starts as there was no mention before of more money needed for a new passenger footbridge across all BR platforms. I have no idea why the existing bridge can't be used so there must be a very good reason to spend an extra £25,000,000
Still wondering how the passengers will end up paying for the link? At the moment passengers can buy a through ticket to Luton Airport but many don't seem to do this so another ticket has to be purchased from the conductor. If that happens for the DART it will remove the seamless interchange.