Fortunately, one of the valid reasons for opting out from a "VPP event" (which is what my battery mfgr's app calls it) is a coming storm. In fact, in my system a "storm hedge" (where the battery tops itself up before a storm) trumps a VPP event, so for all practical purposes, there is little inconvenience. So there aren't really any drawbacks. And when you are done paying your loan you can either stay enrolled in ConnectedSolutions or not.
I say go for it. A 0% loan is great, and it was the deciding factor for us to buy the battery. Honestly, I wish I had bought a bigger battery! 15kWh is good for an evening, but not quite enough if the following day is rainy.
My other equipment is mostly SolarEdge, which is excellent and well-behaved. SolarEdge now has batteries too-- I would probably look into them were I to buy a battery again.
A couple things to note. If you get a battery do not put it near your house. Generally, energy storage has a good safety record, but if they do experience thermal runaway, the fire effectively cannot be extinguished until all the fuel is consumed. Mine is 75' from my house because I have a solar groundmount array. Second, my solar installer initially set everything up using wifi, including a high-gain antenna because the array was so far from my house. I pointed out that I had an ethernet switch in my basement, so they ran hardwired networking through the power conduit to my house. Much more stable. Just ask for ethernet upfront if you can.