It could be worth though there is always some measure of risk purchasing refurbished electronics.
I purchased a refurbished 15.6" Dell Latitude 3540 with a Core i5-4200u, Radeon HD 8850m, and 1080p screen for less than $500 back in January 2014. I purchased it from an eBay seller with a rating of over 98% and I think had over 10,000 sales. It was advertised as have been refurbished by Dell with 10 months left on the warranty. I decided to take the risk since ebay does have a buyer protection plan. Looking at Dell's site a new Latitude 3540 with the same configuration was selling for around $850.
When the laptop arrived everything seemed to be in order. It came in an official Dell box with all the accessories and a statement from Dell stating the laptop has been refurbished with the date of when the 1 year warrant expires. The only problem that developed over time is the number 2 key on the numeric pad sometimes does not register when I press it.
I later found out that Dell was these laptops at their outlet site for $300 each during a the 2013 Black Friday sale. I guess that's why the seller had around 30 of these laptops with the same configuration for sale.
It all depends on who does it and what kind of job they do. I personally work for a computer repair/retail shop, and we refurbish laptops and desktops in house. Typically the process goes as follows.
Test all the hardware and verify there are no bad or failing components. (Extended SMART test on HDDs)
Wipe the HDD and load a fresh install of Windows.
Install all updates, drivers, runtimes.
We typically do not have issues or complaints from customers who by our refurbished systems and many people praise our work. For the money it is a great deal as you are getting similar performance of a new system for about half the price. I purchased my laptop refurbished and its the best laptop I've ever owned.
I would trust manufacturer refurbished, but I've also seen refurbished laptops from Newegg or Amazon that seemed to work, however the hard drives were starting to fail. Keep this in mind and hopefully you get one with a good warranty. Our shop offers 90 day warranties on refurbished systems and we offer extended warranty for up to one year. Hopefully you have a good local shop near by that offers the same.
I have two refurbished laptops (general use). One is an HP and the other a Lenovo. Both were refurbished by a NewEgg third party company and they have worked fine. Keep in mind however you might get one with a scratch on the screen or crack on the case. There are some vendors who will give a refurbished laptop a grade (grade A meaning near new, B being minor visual imperfections, C being very worn). NewEgg does that.
Watch out for companies that advertise a warranty without specifying the length. Some try to get away with a 30-90 day and no return policy. Or language that says they can replace it with a model of their choosing, ie a cheaper one.