Without getting into the ins and outs of .410 vs. 28 ga vs 20 ga, etc., I have a guncase full of 20's and 12's. About a year ago I bought a used 870 Wingmaster in .410. I find that I have had more fun in the past year shooting that .410 than I ever thought I would. I have shot skeet (high round so far is a 23), Sporting clays (did about 60% on that course), doves (you give up 10-15 yards to a 20 gauge, but if you pick your shots you can put 'em in the freezer), and squirrels (no misses so far). The little thing is a delight to carry and just plain fun to shoot. I use 2 1/2 inch shells for all the target shooting and use 3 inch shells on doves.
I can smoke targets better with a bigger gun, but the fun factor is hard to define. There is something satisfying about going to a station on the clays range and smoking 10 for 10 on report doubles and true doubles with a little .410 PUMP in front of 12-15 shooters toting 12 gauge O/U's with 32 inch barrels. Most of them aren't used to seeing a pump gun on the clays range -- much less an itty bitty one.