Eyepiece designs rank more or less as follows:
1 Huygens (17th century), Ramsden (18th century) primitive, not made anymore
2 Kellner or "Achromat" - cheap entry level eyepiece, low power 25mm-60mm, small field of view, common in the 1970's
3 Plössl (OK as a general purpose low - medium power), moderate eye relief, moderate field of view, suitable for 15-40mm focal lengths. In short focal lengths (less than 12mm) eye relief and field of view are very small and orthoscopic would be a better.
4 RKE - good eyerelief, moderate FoV, design suitable for 8-30mm focal lengths, budget eyepiece from about 1980.
5 Abbe or Orthoscopic - low distortion, high contrast, moderate FoV, suited to high power lunar & planetary. Very short eye relief (about nil).
6 Erfle, König, excellent design for medium power, suited to scopes of f/7 or slower. Not suitable for scopes at f/5.
7 Assorted "Superwides" and "Ultrawides". Huge FoV (65-85 degrees) but not optimal with respect to lateral colour, distortion, sharpness.
8 LVW, Panoptic, Speers-Waler, Stratus (barely) or Hyperion (barely) - large FoV (65-70 degrees), good eye relief, design spans the entire range 3.5 to 30mm. LVW and Panoptic are the pick. Excellent with respect to lateral colour, distortion, sharpness. Only negative aspect is large size.
9 Nagler, Ethos - Huge FoV (75 - 100 degrees), sharp edge to edge.
And there is a special case - the Monocentric (planetary high power).
A lot depends on:
- the telescope you will use it with (especially focal ratio) - a Ramsden eyepiece will work fine with an f/15 refractor, for example, but is useless on a fast f/5 reflector;
- who the manufacturer was - there is a huge difference between eyepieces made by Zeiss, Clave, Brandon or Televue (best) vs those from say Tasco or the chinese clones.
- when it was made and the glass types used - great improvements have been made with the advent of modern ED glass types in recent years.
So on this scale I'd rate yours as a 3 out of 9. Eyepieces like this will be fine on longer focal ratio scopes - f/8 or more. But for a scope that is f/4 or f/5 (such as a 10" Dobsonian) you will find it disappointing and very hard to use. For an entry-level dob I would suggest two of the cheap chinese superwides from
www.andrewscom.com.au would be a good idea.
