Is Reddit good for marketing a SaaS app?

Depends how you are going to approach it. If you go for paid ads - you need to benchmark it against let's say Google Ads and see what performs better for your audience. If you want to use communities to promote, as already mentioned here - be aware of community rules and do not spam.

Only if you're doing content marketing that is not an overt pump of your product -- they tend to rip those to shreds publicly. I'd also be careful have metrics on users who do subscribe, as there are many on Reddit who will demand refunds 10s after signing up because they really couldn't afford it in the first place but curiosity got the better of them. It can make churn rates look poor so be sure you have origins assigned to them so you can make sense of churn numbers later.

Reddit is one of the most dangerous means of communication for marketers. The community can be really harsh on commercial messages.

I help a lot of people market their SaaS on Reddit. Here is an example: https://syften.com/blog/post/one...

Reddit is based on micro-niches...in order to get traction on reddit, you need to really drill down to niche>>Sub niche and micro niche...so for example when you talked about marketing a SaaS app...its too broad for reddit community. You know that reddit is divided in to several sub-reddits and each of them are like micro-communities. So if you want to target redditors, you need to join several micro niches related to SaaS app...lets say you have an SaaS that helps to create ticket system for customer service on ecommerce platforms...you need to join subreddits focused on customers engagements on shopify...the point is you need to go micro niche on reddit. You need to perform ultra focused audience research. That is where I think you need to be super specific whom is your target audience. Last week we launched a product CrawlQ on Product Hunt and now we are also coming up soon with CrawlQ reddit add-on...using this you can research the micro-niches on reddit and create more resonating content ideas.... check out how CrawlQ can help for your SaaS app marketing on reddit.