i have two armies atm sisters and ig
But i am getting sick of them.
I have never played anyone with necrons in battle i have the codex and i read but reading is not the same as knowing how they fair in battle.
i have simple questions like
how to they do in combat?
how does the self repair do in a battle? it sounds like 50 50
does summoning troops work as good as it sounds?
The feel is of a 1950s horror movie. The aliens keep coming, are hard to knock down, and they keep getting back up. In the original incarnations they were slow and pondorous. They just formed phalanxes that slowly advanced. Getting near them meant you took a lot of shots. They originally didn't have a lot of close combat forces, so some armies could rush in and fight on their own terms. However, exchanging fire with them at range was problematic.
More recent Necron have more mobility. A monolith can move units around, and can pull units out of close combat so the enemy can be shot. There are some half decent close combat forces.
The horror movie aspect sometimes used to come from a different angle. They have a lot of special rules. Some players used to ask how GW could come up with such horrible rules. I haven't heard this very much of the most recent version. They have respectable overall power and are competitive, but they are not over powered. You don't see play to win folks migrating to Necron.
The big question is why you are growing bored with Sisters and Guard. I sometimes get sick of armies when all battles become too much alike. Some GW armies are very focused, have firm themes, demanding that you play the army the same way every game. If all units in an army are more or less alike, you have to build your tactics around the common "what we do well." If one does that too much, there isn't a lot of variety in the games.
My first two armies were Eldar and Chaos. The Eldar have a wide variety of highly specialized troops. You can play many different styles. When I started Chaos, I could mix fast demons in light armor, shooters in heavy armor, and masses of cultists in no armor. Such diversity allowed me to build flexible balanced armies, or allowed me to created a highly specialized army that the other guy across the table might not have seen before.
Necron.... Most of the armies are pretty much alike. They play pretty much alike. There are more options than there used to be, but the units that break the standard Necron mold are expensive in points and are in elite, fast and heavy slots, so one can't really take enough of them to break the mold. There is only one troop choice, so one ends up playing a game that optimizes how to use the troops. Said troops are incredibly tough, but are otherwise fairly routine.
Or that's my opinion, anyway.
