The reservoir size is very ideal for hand pumping. I have had one, I tuned it up for a friend. It's a very simple design, and just plain works. (I have a couple pistol version of this rifle, too).
One thing to look out for is moderator alignment. The narrow end of the moderator butts up against the front sight post which is plastic. All the ones I've seen have a bit of a plastic mold line there, and this can cause the moderator to sit a little crooked. All you need is a flat file to fix (if it's an issue). I've had to align moderators on a few other guns, and the procedure is the same. Remove a small amount of material, and check. Repeat til straight. Patience is key.
Other than that small issue, It's a very simple design. And they shoot very well. The only downside is the power output has a good bit of a bell curve. Meaning it shoots very hot at high pressure, and steadily drops power from there. There will be a small sweet spot where the gun shoots a few shots at the same velocity (roughly). Usually keeping the velocity steady or consistent lends to more accurate and repeatable shot placement. One way to achieve this is to install a regulator. I believe wes @ airgunarcheryfun sells these with them pre-installed (if you chose that option) and for a good price, too. Now, a regulator will reduce your max power in this gun. But It will greatly increase the number of *highly* accurate shots you can get out of it. And quite frankly, would still be well above the power output of several airguns I hunt with. Another option is to detune the hammer strike. If done right, that will flatten the power curve, so that you get a larger number of shots shooting more similar velocities.
Even without tuning or installing a regulator, the gun shoots plenty good enough to take game within about 40 yards for a pretty decent number of shots (20) Without really worrying about the gun not being a complete tack driver.
Those are my two pistol versions, BTW. One has a regulator, one does not.
