It used to be great

Alex's mobs is one of those mods I used to really enjoy as a player. A good chunk of the mods are incredibly well designed and textured and when I was playing packs they played really well. Even a lot of the modern mobs still have great textures, and if you just want to build a zoo or play in creative that's all that matters.

In survival however, configuring this mod is a mini nightmare and the amount of mobs that have been added, some of which don't live up to the quality of others makes this mod very hit and miss. For a mod that describes itself as incredibly customisable this isn't good enough. Making a pack with this mod can be a chore.

Then, the performance, many of these mobs have quite complex AI and spawn so frequently that this mod can be a nightmare on servers, it can bring entire packs down to a halt especially if spawns haven't been significantly reduced. if you are a server owner, I'd advise turning all the spawns down significantly.

Try this mod out in creative, maybe try it in a small pack in survival, but I wouldn't recommend this on servers.