The spelling is egregiously bad, of course, with U and V scrambled and apparently some randomness in the rest. The effusive dedication to Queen Elizabeth was pretty off-putting too. And I’m not about to try to address the symbolism on the first go-through: just getting the language straight is enough for now.
Once you get into the rhythm it flows very well, except for dramatic scenes. The suspension in that 9’th line trips up battle descriptions. The scene with Despair persuading the knight is powerful, and the overall tone--almost nobody is trusty--is striking. Many of the descriptions show good attention to detail while remaining clear and flowing. I prefer Bunyan’s "Palace Beautiful" to the "House of Holinesse" and its rather extreme ascetic drills in purification: the forthright allegory in that section begs for the comparison, and Bunyan wins. Though having "Charity" be married with many children is a good touch. Spenser isn't shy about what the usual benefits of the conquering knight are with his late opponent's lady.
Spoiler alert: The Red Crosse Knight is told he is going to be St. George, which jars rather amusingly with the history of the real one.
The Kindle version I have is defective: the original and annotated versions are intermingled, which in the original format were fine but makes this one rough sledding--and there are enough obscurities that I need the annotation. I'm not quite in the swing of language yet either, though no doubt it gets easier as you go along. So, bottom line: I'm glad I read this, but I'm not sure I've got the time to address the other 5 books.
Your mileage may vary.
To illustrate: The Red Crosse knight defeated the Saracen Sans-foy and acquired Duessa (a dubious reward), and on reaching Duessa's beautiful but malignant castle finds himself challenged by Sans-foy's brother. The Queen here is not the titular queen but Pluto's daughter.
At last forth comes that far renowmed Queene,
With royall pomp and Princely maiestie;
She is ybrought vnto a paled greene,
And placed vnder stately canapee,
The warlike feates of both those knights to see.
On th'other side in all mens open vew
Duessa placed is, and on a tree
Sans-foy his shield is hangd with bloudy hew:
Both those the lawrell girlonds to the victor dew.