Well, you can check with varoius domain value sites, though the price values will be all over the board as there is no hard and fast set of rules for pricing a domain. The biggest benefit to this domain is it's age. Your best bet is to sell it on Flippa, Digital Point, or a third party domain broker (check google).
If you want to develop it, a simple affiliate/review site won't give you enough SEO power in that niche to do much good unless you are going to integrate Offline marketing.
I have a software (custom developed) that I can gather virtually any number of poker sites into a database (site name, url, unique description, etc) so you could create a massive site (my suggestion is 100-500 pages) and develop an authority presence in the niche. These types of sites in my tests get a LOT of longtail traffic.
PM me if you are interested. Otherwise I'd say if you're not into building an authority site just hang on to it or see what you can get for it on the sites I mentioned.
Good luck!