I played some operational naval games from Avalanche Press but really wanted more involved (but still playable) tactical system than they offer.
Two features I like the most in Command at Sea system are the modular structure of the rules (so you could dispense with aircraft and submarines for starters and play just surface engagements with few ships per each side) and the fact you could play using mininatures, counters or just plotting ship courses on paper. That makes this system really accessible.
There's also a lot of supplements which are worth buying in themselves for the plethora of information they contain.
I'm really looking forward trying this system.