The LCS capability is one of promise and potential, but because it really rewrites the book in terms of US Navy operations there remain many questions.
The first issue is the lack of firepower. This is the only capital ship I can remember in the last several centuries any western Navy building that is intentionally designed to fight small boats. It takes a lot of imagination to come to a conclusion that a 3000+ ton ship should be built to fight a fleet of boats more closely resembling the Miami County Yacht club than a true military force. However, today that is the expressed interest behind the anti-surface warfare capability of the LCS.
The emphasis of speed is questionable. 40 knots sounds great, but when reading what is out there on the LCS CONOP it can leave one scratching his head. The CONOP describes the LCS role in ASW and MIW in cooperation with a Carrier Strike Group as racing ahead of the strike group to insure safe sealanes in the approaches for the Task Force. The problem is, that CONOP was described in a large scale confrontation situation, ie China, which means the LCS is going to race out in front of a CSG and do ASW work in a war against China? Seems to me that Admiral would have questionable judgement to put his least defensive ship outside the screen of a task force, between the task force and the enemy no less, and expect the enemy not to exploit the situation and blow the LCS to hell.
Regarding ASW and MIW, a lot of these sensor technologies are new, as in they have never been used. It is a fairly substancial gamble to risk two critical warfighting capabilities on never deployed capabilties designed around a fast ship for 2 mission roles that inherently require slow speed for operation.
Finally, the major capability increase of the LCS is its distributed sensor systems integrated with CEC (integrated C4ISR). The problem there is that the maturity of the distributed sensors doesn't exist, and oh ya, niether does the maturity of CEC. CEC is limited by 19 nodes total, and while the Navy is trying to expand that to 49, it hasn't yet. 19 nodes isn't many at all, think about it.
2 CVNs
2 CGs
8 DDGs
4 SSNs
1 SSGN
2 E-Ds
Oops, that's 19, no room for the LCS, and the Navy is more likely to include an EF-18G, a P-8, or a Global Hawk (nevermind other large surface combatants) than a LCS in a shooting fight, which isn't going to help the LCS much, particularly since it doesn't have much to defend itself with.
The LCS may go on to be a fantastic ship, but at this point there is a considerable amount of risk involved beyond just the cost.