To be honest, initially I found Marin a little daunting. It was the first time I'd used a platform of this type and the tool seemed like it would have a steep learning curve. Turns out my apprehension was totally unfounded. The UI (despite looking a little clunky) is actually quite user-friendly and easy to use, and the learning curve is accommodating for both SEM newbies and vets.
What I liked best, however, was the customer support. Our rep, Jeff, provided training that was simple, informative and got our team up to speed incredibly fast (honestly, other tech companies could take a lesson from Marin's training). Marin staff also answered all of our emails within minutes and were always free to jump on the phone to walk us through a question. A tool like Marin is only good as the individual using it, and Marin made a huge effort to ensure our team was as comfortable as possible so we could get the most value out of the platform. In fact, one big recommendation I have is to user their Workflow Guide, which I found quite helpful for walking me through some recommended actions on a daily, weekly and monthly basis.
I also absolutely love the View Builder feature, which allows you to get quick, high-level views on campaign performance (something that's a bit more difficult to do in AdWords). The reporting and alerts features are also amazing, letting you stay up to date to sudden changes without having to dig through a large amount of data.
While the campaign management features of Marin are phenomenal, the real value of the tool is in its Bidding elements. My agency was a little skeptical about Marin's boast of improving conversions by 20%, but that's exactly what we found for the first client we ran through bidding. Conversions increased and CPL went down. It was honestly as simple as that (we even went into AdWords to confirm that the numbers were right, since we couldn't believe how effective the bidding algorithm was).
My biggest complaint is with Marin's calendar tool. It's a bit clunky to use and I initially found it difficult to tell which dates I was drawing data from (once you get used to it, it's not too bad, but definitely something that could have been improved). I also found that the reporting setup could be a little buggy from time to time (I actually had to file a ticket at one point with Marin's IT team, but the issue was resolved quickly).
In general though, there's very little to dislike with the platform and most of my complaints are minor gripes at most. It's an incredibly powerful tool.
We really wanted two things out of Marin: to be able to manage our Search and Display campaigns more effectively (in both Google and Bing) and to be able to improve conversion rates.
Marin allows us to do both. We save time, save effort and get more value out of our client's online marketing budgets. I cannot recommend Marin highly enough.