I recently switched from a small Stihl gas trimmer that gave me almost two decades of service to an EGO battery powered trimmer. It's different, not doubt, but overall I like the EGO. Quieter, yes. Much less vibration - I really like this bit. Carbon Fiber shaft. Power wind for the trimmer line is pretty sweet. Carbon fiber shaft. Decent balance with the 5.0amp battery. I'm generally satisfied with the power of the trimmer. It handles everything my Stihl did and often a bit more.
Pulling a rope to start isn't hard on a properly working gas trimmer, but just pulling the trigger is even easier. No gas or oil to buy/mix/store. No spark plug to change. No tune ups. These are not major challenges with a gas trimmer, but put all the little pluses together, and I've found my battery trimmer to be pretty nice.
EGO's batteries come in the same volts but different amp hours, so mileage will vary accordingly. Beyond that, battery life depends on how I'm cutting. Full blast, non-stop in extra tall/woody stemmed weeds/gras and I can be out of juice in 20-35 minutes. Short bursts at half power in regular height grass and it can last close to an hour.
If you need more than one full charge, the options with my EGO are to take an extended break - about an hour (standard re-charger), to buy the quick recharger which is supposed to cut recharge time down to about 20 minutes, and/or buy a second battery so you can keep swapping and recharging. So far I've done made do with the regular charger, but I'm looking at another EGO tool. If I buy it I either spring for the quick charger, the second battery, or both.