Well currently the Celeron processors are the cheap old style so do not expect power to run lots of programs etc.
It would be good for using office for most tasks, playing simple browser or casual games and browsing the net.
It would not be great for high power requirement programs, video and photo editing, most games and running multiple progams.
I would not pay more than 250 for that setup in a laptop, 270 is probably asking a tad too much without some thing to sweeten the deal, like some extras included.
I think I read it had office 2010 and windows 7... therefore actually it looks a bit more good value
I have an acer, never had any problems. Normally I would say buyng electronic equipment from ebay could be risky, but having checked the seller there will be no problems. Bought from that company a few times and always had good service