Looks good, doesn't look out of place compared to "modern" bikes in my opinion.
Might build one for myself one day, maybe use my daughter's or wife's one instead in mean time.
Do you see the wee bolt on underside of top-tube above shock? Took me a while to work out what it was for, had an idea but wasn't until I saw a pic of another Marin that it was confirmed. You might know already, of course, but it holds the brake cable/hose and gear cable up off shock with, originally, a rubber loop. It's not on the small 15" East Peak my youngest has but it's on the 17.5" Wolf Ridge my oldest has. Now await someone telling me that's bollocks.