I have used NetApp and Dell Unity. Dell Unity has more features

The Lenovo DM Series is an excellent storage product, but I think it isn't competitive with other companies like Dell EMC and IBM because IBM products are very cheap and have more features. 

We previously used the V3700, which is also from Lenovo. The product was at the end of its life which is why we switched.

This solution has been in place and part of our IT department since the beginning and we have had no reason to change.