They offer a base system (100MB) with no up front equipment cost, other then a shipping charge for the kit which is a rental with no actual rental fee. Noting that the equipment must be returned if service is cancelled.

What she needs it for is email, OOMA phone, and ROKU streaming.

What I am wondering is if anyone here has anyone here has had any experience with the service.

Does it seem to maintain decent speeds? Any issues with weather drop out?

Cost is about the same as all the other services, but Spectrum is the only one available at her location at the moment.

Starlink Gen3 is Shielded Cat6 dish to Gateway.

The switch is imminent though, since Spectrum is being a problem. The service goes out pretty regular, and when it happens it takes them several days to fix it, and then they are going to raise the price again.

Looking to the low bucks deal for the old gal as her budget can't handle another increase.

1) Speeds are going to depend on the region and congestion of the network in that area. Speed will also vary as the dish is tracking satellites across the sky. The minimum speed I get is 150Mbps at the fringe and 450Mbps as the satellite move overhead. Averaging about 200Mbps thru the day. I'm in a good area however.
Also, how open the sky is will make a difference. There is a 3D render in the app, that will show you how much of the sky is clear to the satellites. It takes an hour+ for this to populate completely. I have 100% clearance to all horizons. Other systems that I've installed that have a much more limited view, tend to have less speed overall.

2) YES, rain will affect signal & speed. During a very heavy downpour, you can lose signal completely. This is very rare, as it takes extremely thick cloud cover and rain (takes much more than it would take to knockout DirecTV or Dish). But it can happen.

3) You didn't mention price. Normal service is $120 per month. But in areas with more competition, it is offered for $60 per month.
You can also put the service on pause for $5 per month. You can still use it with speeds under 1Mbps. But recently dirty tricks are being played on customers. When you take it out of pause mode to regular again, many are now reporting getting hit with $1500 bills to do so (they mention congestion of service in an area as the reason - I call BS). Until this is resolved, I would not recommend pausing the service at anytime while using it.

4) As I and others have mentioned hundreds of times, Speed tests when you are only looking at the speed is near useless. That only tells you 1/2 the picture and not even the important 1/2. "LATENCY", that is what's most important about ISP quality of service. Starlink in my area averages 15-25ms. Also your "latency under load" is very important. I get 20-30ms down under load latency & 20-30ms up under load latency.

So the service is pretty solid.
Just did a test while posting this [19ms latency static - 218Mbps download w/25ms latency under load - 40Mbps upload w/24ms latency under load]

She has wide open sky near the house, so that shouldn't be an issue. As far as cost, I'm being offered $50 a month for 100mbps which should be sufficient for her needs.

A lot of the time she watches off air, and only sometimes a Roku stick, and the only other thing online is a OOMA.

The other offer in her area is T-Mobil 5G, but it comes at a higher cost.

Strange on that T-Mobile 5G. Usually the cost is $60 per month if it is standalone. And $35 per month if you bundle with you're provider. Verizon, AT&T, T-Mobile all do this and use the same or similar equipment.
That makes it one of the cheapest options. Again speeds are going to vary be region/location. All the ones I've installed around here have similar speeds to Starlink (the max plan).
The biggest thing with the 5G service (at least around here), is that latency. The static test is usually around 35-45ms. But when you put it under load .... latency jumps to 100-150ms (up & down). That makes it feel very sluggish and causes some issues with some services. So at least around here, 5G internet service is either a last resort. Or for someone needing the cheapest they can get (bundled with their mobile provider).

Her YouTube TV is also "free" to her, and the Roku is also shared.

This is as low buck as you can get....:-)

Hell, we pay her property tax, car payment, insurance, and a lot more... It's just what ya do.