Worth the money
I was having a difficult time getting another brand OAG to see the guiding stars. With all the available accessories, it was easy with the Celestron OAG.
Celestron Off-Axis Guider
excellent as advertised
Great and fairly simple to use for an OAG
First, the unit is huge, but allows for an easy adjustment of guider position and camera orientation. I use a Canon 5D Mkii DSLR and ZWO ADI174mm Mini guide scope and connecting them both was easy, only needing an M48 T-adapter setup. The depth of the DSLR and thickness of the domed OAG adapers required raising the guidescope almost to the top even with the 25mm nosepiece to achieve parafocus. But, it was attainable and the prism reflected plenty of light for the guidescope to find stars easily. Many configuration adapters are provided for versatility (M42, M48 etc). Note that the OAG can be assembled backwards as the interface on both sides of the OAG body are the same. So pay attention to the orientation of the prism.
Celestron Off Axis Guider
It has been a great experience. The unit is massive compared to others and has a smooth guide focus without having to twist the guide camera around in the focusing process.
Nice but huge
This is a very nice OAG, but be aware it is very wide. The body is the stated 29mm, but the adapters front and rear will add another 15 or 20 mm. Otherwise, solid, nicely made and comes with lots of adapters. The focuser is very nice.