Hopefully others will reply and give an honest opinion of iCodes, but I can assure you it is extremely well maintained and has 98% of the merchants from across 14 Network, and 98% of the voucher codes, and most of the worthwhile deals.
The reaons we don't have 100% of the merchants and 100% of the codes is because codes and merchants are added constantly and there maybe a delay to include a code, or a new merchant, the reason being each code details are manually checked / edited if required and categorised before going live.
If any code, offer or merchant missing the user can add them within seconds anyway, so natuarlly the more users we get then the more accurate, upto date and more policed the database becomes.
Our webservices is extremely powerful and can be used live or imported into your own database, we have sample coding examples and even a free fully working voucher site you can download, also their are other third party scripts available which import out feeds such as the iCodes WP Plugin, Denovo Voucher Script and CouponPress Wordpress Script..
Our services includes a lot more than the above but hopefully that covers your questions :-)
We are not the only feed agregator on the net, there is also Promotions.co.uk and Vouchers.im