I have been using it for almost 1.5 years and really like it. It takes a moment to set up and has way less features than Mailchimp (less third party integrations, segmentation features etc.), but the price is awesome and Amazon SES is also very cheap. I haven't been using it with Digital Ocean (so don't know how well that works).

Amazon SES also has very good IPs. If you check them on https://senderscore.org you will see they usually rank above 95%. The only problem is Amazon SES strict policy against bounces and complaints. So your list has to be very clean and ideally double opt-in before you can send. Also Amazon SES starts you out with 10k emails/day and 5emails/sec. You need to ask for a quota increase (which was always granted in my experience) before sending higher volume faster.

My tip: If you have some old/invalid emails that you know will cause problems with Amazon SES, send to your most active (recent openers and clickers) first and then gradually introduce your older emails. Monitor your bounce and complaint rates to stay below 5% and 0.1% respectively.