I like that it's easy to use, well thought out product from someone who has been in this business for years! It is very flexible when creating campaigns - we have had success using both display as an overlay ad unit combined together or separately depending upon our need at any given time (and what works best).
The support team are also fantastic; they're always quick to respond via email/phone whenever needed which makes things so much easier than having to wait days between responses if working over long distance hours / weekends etc.. There really isn't anything bad about BuddiZ other then perhaps its price could be cheaper? We've used them since 2015 but now pay around $50 per month compared to others paying upwards of £70-£100+ monthly just because their products aren't quite perfect yet & still improving each release!! But once everything comes online there will not even compare anymore unless maybe something better pops up along side :).