Tough to tell without a picture of some sort of the house and the yard.

Kinda depends on how you want to use the space. And, would a patio be wider? If you want space for multiple chairs/furniture in a row, sounds perfect. If you want groups of furniture, not so great.

Why not play around with those dimensions on a CAD program and see.

I don't think the proportions sound very pleasing for a typical home deck. It will feel much more like a long balcony than a deck where folks can gather in a circle and have conversation. The two corners allow small conversation areas, but that is a lot of space between. If you have a great view then a row of rocking chairs or adirondack chairs will work great and feel good with room to walk behind them (like at a beach or mountain lodge). I would suggest a 10x12 where a small conversation area and maybe a grill could be created, but use the deck primarily as a transition to patio below. The patio can become the space where larger groups gather, the dinning table is set, and the fire pit is stoked. Pics are need for better advise. Good Luck

I think ten feet will seem cramped, but if you open up the other dimension it can ameliorate that feeling. I just put in recently an 11 1/2 foot patio cover at the back of the house where there were some heavy duty constraints about going deeper (silly things like trees and rocks and dragons), and the more we stewed over it the more it bothered us. We decided to go the full house width and it completely changed the entire gestalt of the project. It feels like we're in a nearly different place. Play with your plans, and ask people who are over to look at your sketches. You may find a better layout.