As a former customer (it has admittedly been a few years) I'm not surprised. Sendgrid's entire business is based on price. Emails are one of the few costs that don't really scale that well. They cost a lot more than people think they should. When I list did a cost analysis they beat out a lot of other providers.
I haven't used them in years, so I'm not sure if they are still the low cost leader, but they are definitely the kind of thing where you get what you pay for. Their lack of investment in product and infrastructure showed for the years I used them, and their slowness in delivering updates was incredibly frustrating.
I'm not the person you asked but I too have had bad experiences with SendGrid.
It really depends on which aspect of SendGrid we're talking about.
Transactional e-mail? Mailgun is a easy to use API on top of Amazon's SES.
You can even set up incoming e-mail hooks e.g. "When a new e-mail arrives, POST the contents to this address and attach any attachments on the e-mail as file uploads."
Newsletters? Drip campaigns? I have less experience on this side of the realm, but HubSpot has been the best experience I've seen. Their web management UI is also powered by their own open API, if I remember correctly.
I like mailgun, but I am having a devil of a time with them sending to MSN and aol addresses. Basically 0 deliverability. And their tech support is going on 4 days without looking at my ticket. But maybe it's not their fault.
I haven't used them in years, so I'm not sure if they are still the low cost leader, but they are definitely the kind of thing where you get what you pay for. Their lack of investment in product and infrastructure showed for the years I used them, and their slowness in delivering updates was incredibly frustrating.