I think the Dell EqualLogic line is neat for what it is, expandable block storage with a unified management interface. But there are some weaknesses.

• iSCSI
  The EqualLogic line is a block storage line; iSCSI is what you're getting unless you purchase a separate NAS head to install and run CIFS or NFS. When looking for shared storage, iSCSI is usually the last type organizations should be looking for. Of the leading virtualization platforms out there, Xen and vSphere prefer NFS storage. Hyper-V is the only one which requires iSCSI.
• value basis
  Dell already sells 12 bay, 2U servers which can be filled with whatever drives you want for a RAID configuration you need, the R510 and R515.
  http://www.dell.com/us/enterprise/p/poweredge-r510/pd
  http://www.dell.com/us/enterprise/p/poweredge-r515/pd
  For software to run on top of the hardware to share the storage as a SAN/NAS, there are great options like Nexenta.
  http://www.nexenta.com
  It has a community edition which allows you to manage up to 18TB free (for non-production use).
  http://www.nexentastor.org/projects/site/wiki/CommunityEdition
  
  If you want flexible SAN with commercial support from a Tier 1 vendor, check out HP's Lefthand P4000 Virtual SAN Appliance which will run as a vSphere appliance on any server on the vSphere HCL. Put it on the R510, the R720xd, or the HP DL380 and get Tier 1 support for the hardware and the SAN software for less than the cost of an Equallogic, without the SAN software license being tied to the hardware it's on.
  http://h18006.www1.hp.com/products/storage/software/vsa/index.html
• incomplete feature set
  As John773 points out, it's a multi-controller array that doesn't really do non-disruptive updates. See Updating Equallogic SAN Firmware /w CSV
  http://community.spiceworks.com/topic/245101-updating-equallogic-san-firmware-w-csv