The first thing I'd like to get out of the way is that yes, the esper is phenomenal. Fully constructed, the esper is sturdy and provides outstanding output with a relatively easy prime. It looks good, feels good, and packs a punch.
That being said, there are some things buyers should be aware of. Some may find constructing the blaster to be arduous. There are nine different styles of small, silver screw that all come in the same bag. These screws are difficult to sort and, if used in the wrong part of the blaster, can lead to irreversible damage. I spent roughly 20 minutes just sorting between several types of near-identical screw before I even started on the kit.
The directions can at times be confusing or misleading as well. Be aware that you may need to reference other sources and/or use trial and error for assembly. The most frustrating thing for me was that the screws provided to hold the barrel in place did not do so, and I had to use another size (the PT2. 3*6MM) to keep my barrel from falling out.
Overall, this kit was well worth the effort spent. If you don't mind a bit of troubleshooting and you want a high-end blaster ASAP, I highly recommend it.