It's pretty straight forward - all the fees and conditions are laid out and clear.
I haven't used it myself but a neighbor of mine used DFS to buy 3 systems (1 laptop for a college bound daughter and 2 reconditioned PCs for his business) and had a good experience last year. The laptop was a 'no interest if paid in full after 9 months' special offer.
On the negative side there have been some legal issues. My take; if they could 'legally screw' you - they'd try. Since that adverse judgment they'll be less likely to take chances, IMO.
Since you know they're not out to 'give away money' you also know they're not necessarily going to have your interests foremost in any transactions.
It might work out best for you to use some of those 'coupon codes', get a good upfront deal and either pay cash or use a personal credit card, especially if you have lower CC rates than whatever rate DFS will offer you.