The downside is that the batteries are now dead, after only 2 years usage. According to Dell that is good going, about 500 recharges I estimate, but Dell reckon 300 is average. I was expecting closer to 1000 based on ordinary rechargeable batteries! That doesn't work out cheap at 77ukp +P&P +VAT.
Did you have the batteries plugged in while you ran the laptop on mains power? that tends to kill them fairly quickly. Of course that is not as bad as the original sony laptop battery on my Vaio I had, which died after about 35 charge cycles.
Adam