I like that they are very proactive in their approach to our business needs - we have had them for many years now so this is something you get used too! They also do some good work with other organisations as well which helps us out when it comes time to deal with others who may be difficult or just not interested at all but need help anyway (sometimes even if its only 1 hour).
Nothing really!! We use solnets services mainly because of how much value there has been over several year's worths compared to what would otherwise cost me more than double by using my own team/department etc..