Just received my (1 month) Thunder SIM today and initial speed tests give a fairly respectable 25 - 50 Mbps download but a miserable <1Mbps upload speed here in the BKK suburbs.
It is evening and therefore peak time now, however, so perhaps it will be better during the day. I also haven't experimented with relocating the phone much.
Still, I think it should work for my needs - we've moved back to the UK now but will visit TH several times a year and will need to work, so I want to keep some sort of internet alive at our house in a muban. This could be a good cost effective solution. We need unlimited data or certainly a high data limit (>200GB / month) as we're both working remotely.
Although this time I bought a 1 month True 5G unlimited tourist SIM for 1199 baht which has worked well, but NT Thunder might be a cheaper option going forward. We're at over 100GB usage 10 days in here, hence the requirement for large amounts of data.
When trying to do a bit of research about this SIM online (mostly on pantip translated via the browser) it looks like the reason the 12 month 999 bath Thunder SIM isn't (officially) sold any more is because NT will lose the rights to the band(?) at some point in the middle of next year, so the service may discontinue. Not sure if anyone can shed any light on that?