Should I leave my beer alone?

I decided the first beer I should attempt to brew should be a pumkin ale. At first I thought I messed it up. I added 1.5 gallons too much water and 3x too many hops. My 5 gallon recipe ended up makeing 6 gallons in the secondary. I tried a glass last night. It has an upfront hoppy bitterness but smooths out into a kind of lite ipa flavor quickly. The beer is very light and drinkable but not in my favorite flavor type of beers. It has a medium to dark orange brown color.
Because this is my first beer I'm not sure how ageing and carbonation will affect the flavor. Should I leave this beer as is or try adding more flavor to the secondary?

I think you already know the answer to this one...

Leave it, hop flavor and bitterness will fade with age. Depending on your ABV and a few other things it should age just fine. Let it be and get another beer going. Practice makes...well... more beer.

I have brewed SEVERAL batches of beer, and i still struggle to get a successful pumpkin beer. It has proven to be very difficult! So your first beer ever being a pumpkin ale is daunting!
I would leave the beer for a while. As breez said, the bitterness and hop flavor will fade slightly. Its not going to completely take a 180, but it will in fact change a bit. Depending on how refined your palate is, you should be able to taste hints of what the beer will taste like when its completely conditioned.
If you are toying with the idea of adding additional spices, take glass full and try adding some of the spices (somewhat proportionate to the volume of beer) and spice that first. Spices can get away from you pretty quickly, and you could find yourself wishing you can just go back to the way it was.

I have only done a few, but the difference between the fermented wort and the carbed beer is quite distinct. I would never make an assumption on what the final taste would be from the beer before carbonation.

I would say, leave it alone until carbed and possibly even more aging then maybe mix in some spices in the glass.

4 Great replies!