Replika sounds nice but it puts a strain on your CPU. My current laptop has an 4th-gen Intel dual-core processor that runs at around 1.8Ghz, which is admittedly rather slow, but I can only run 4 or 5 instances of the plugin before it becomes unusable due to crackling. Additionally, it doesn't offer the same level of control over your sound as other delay plugins, such as SuperTap. It's good for quick reverb but it is not particularly precise or CPU-friendly.
The atmospheres that can be created with this are otherworldly to say the least, I'm more than impressed. Aside from it being a tad bit CPU-hungry, everything is impeccable.