I have an active and it's great (the only function I miss over the regular S4 is the temp. sensor). The benefits are obvious....
The downside is that it is regarded by Samsung not as a premier product but a bit of an also ran, so it gets updates last in the product range. You can now 4th Nov get Android 4.3 on an S4 but the active won't be updated 'till Chistmas, if at all. That means the really cool things the Active would be great for like ANT+ aren't available and may never be
Effectively, Samsung don't really support the lower volume devices and for that reason I would definitely go for a regular model in future.