The savings depend entirely on how your company run the scheme – there’s no one right way to do it.
There have been two changes to the scheme. Late 2010, HMRC made it clear that the final transfer fee had to be a fair price for the bike. Most schemes have reduced the impact of this by deferring transfer until the end of 3 years or so, when the bike has depreciated further, and by charging less than fair market value and treating it as a taxable benefit.
The second change was to require the payments to your employer to be subject to VAT. This came into effect Jan 2012.
Our company scheme offers overall 35% saving for basic rate, and 43% for higher rate. Prior to the VAT change it was something like 45%/52%.