SendGrid provides the best analytics a competent postmaster needs. This is not an easy challenge, but if you are really serious about a well-executed mail plan, then SendGrid should be your prime choice.
Other than that, its pricing is fair and you get quality support with the high volume plans.
Improvements to My Organization:
Sendgrid has enabled us deeper visibility to our email performance that simply wasn't there with our previous ESP. with it, we could avoid making pitfalls and tune our practices, so deliverability, open and click rates rose significantly.
Room for Improvement:
They are backlogged on feature requests, which is a bit of a shame really. There are easy fixes here and there that can make workflows smoother.